Equine Sarcoid

Equine sarcoids represent the most common skin tumor affecting horses worldwide, comprising a significant percentage of all equine cutaneous neoplasms encountered in veterinary practice. These locally aggressive tumors arise from fibroblasts, the connective tissue cells of the skin, and are associated with bovine papillomavirus infection, though they do not behave as typical viral warts. Sarcoids can occur anywhere on the body but commonly develop in specific locations including the head, ventral abdomen, sheath, and areas of previous trauma or scarring. Understanding equine sarcoids is essential for horse owners because these tumors, while not life-threatening in most cases, can significantly impact a horse's comfort, usability, and value.

Equine sarcoids occur with high frequency across horse populations globally, affecting horses of all ages, breeds, and uses, though certain demographic factors influence susceptibility. Prevalence estimates vary by region and population studied, but sarcoids may affect a substantial percentage of horses during their lifetime. Young to middle-aged horses between three and ten years appear at highest risk for initial tumor development, though sarcoids can occur at any age. The condition occurs in horses, donkeys, mules, and zebras, with some evidence suggesting donkeys may develop particularly aggressive forms. Geographic distribution is worldwide, with sarcoids representing a ubiquitous concern in equine medicine.

The impact of equine sarcoids on horse health and welfare ranges from minimal cosmetic concerns to significant functional impairment depending on tumor type, number, size, and location. Sarcoids are classified into several types including occult, verrucous, nodular, fibroblastic, mixed, and malevolent forms, each with characteristic appearances and behaviors. Some sarcoids remain stable for years causing little problem beyond cosmetic concern, while others grow aggressively, ulcerate, attract flies, interfere with tack placement, or develop in locations compromising vision, breathing, or limb function. The psychological impact on owners concerned about the appearance and progression of visible tumors also deserves recognition.

Treatability of equine sarcoids is complicated by their tendency for local recurrence following many treatment modalities, making treatment selection challenging. Numerous treatment options exist including surgical excision, cryotherapy, laser ablation, intralesional chemotherapy, topical medications, immunotherapy, and radiation therapy, each with advantages and limitations. Treatment success varies based on sarcoid type, location, size, number, and previous treatment history, with some cases achieving complete resolution while others recur despite multiple treatment attempts. Early treatment of small sarcoids generally yields better outcomes than treatment of large or previously treated tumors. A thorough understanding of sarcoid behavior and treatment options enables informed decision-making for affected horses.

The primary cause of equine sarcoids involves bovine papillomavirus, specifically BPV types 1 and 2, which infect equine fibroblasts and induce tumorigenic transformation. Unlike typical papillomavirus infections that cause productive warts, BPV in horses establishes a latent infection where viral DNA integrates into host cell chromosomes without producing complete viral particles. The viral oncoproteins E5, E6, and E7 disrupt normal cell cycle regulation, promoting uncontrolled fibroblast proliferation and tumor formation. This unusual host-pathogen interaction explains why sarcoids behave as locally aggressive tumors rather than typical viral warts that eventually regress. Understanding the viral etiology has important implications for treatment strategies and infection control.

Genetic and breed predisposition plays a significant role in sarcoid susceptibility, with certain horses demonstrating markedly increased risk based on their genetic background. Research has identified associations between specific equine leukocyte antigen alleles and sarcoid development, suggesting that immune system genetics influence whether BPV infection leads to tumor formation. Certain breeds including Quarter Horses, Appaloosas, and Arabian horses appear overrepresented in sarcoid populations in some studies, though breed associations vary by geographic region. Familial clustering of sarcoid cases supports the hereditary component, with offspring of affected horses facing increased risk. The interplay between viral infection and host genetics determines individual susceptibility to clinical disease.

Environmental and management factors contribute to sarcoid development through mechanisms affecting viral transmission and host susceptibility. Flies, particularly face flies and stable flies, are believed to serve as mechanical vectors transmitting BPV between animals and potentially from cattle to horses. Trauma and wound sites appear to provide entry points for viral infection, with sarcoids commonly developing at sites of previous injury. Geographic proximity to cattle may influence exposure risk, though direct cattle-to-horse transmission routes remain incompletely characterized. Management practices affecting fly exposure, wound prevention, and contact between susceptible horses may influence sarcoid development risk.

Risk factors for equine sarcoids include age, with younger horses often developing initial tumors that may then persist or multiply over time. Previous sarcoid history dramatically increases risk for developing additional tumors, likely reflecting both genetic susceptibility and reservoir of latent viral infection. Wound sites and areas of scarring face elevated risk, providing routes for viral entry. Immunocompromised states may increase susceptibility or allow progression of previously controlled infections. Geographic location and associated fly populations affect exposure risk. Horses with affected family members face increased genetic risk for sarcoid development.

The pathophysiology of sarcoid development involves a multi-step process beginning with BPV infection and culminating in tumor formation. Viral particles likely enter through skin breaks, with flies serving as vectors. Following infection, viral DNA integrates into fibroblast chromosomes, establishing latent infection. Viral oncoproteins alter cell cycle regulation, promoting transformation and proliferation. Different sarcoid types likely reflect variations in viral gene expression, host response, and tumor microenvironment. Occult sarcoids represent early or indolent disease, while fibroblastic and malevolent forms demonstrate more aggressive behavior. Trauma or irritation of existing sarcoids often triggers transformation to more aggressive types, explaining why inappropriate treatment attempts can worsen prognosis.

Early warning signs of equine sarcoids may be subtle, with occult forms presenting as circular areas of hair loss, altered hair direction, or mildly thickened skin that owners may initially overlook or attribute to other causes. Careful owners may notice small nodules, areas of roughened skin, or subtle changes in skin texture during grooming. Early verrucous sarcoids appear as gray, scaly, wart-like lesions that may be dismissed as minor skin irritation. Attention to any persistent skin changes, particularly in common sarcoid locations, enables early detection when treatment success is optimized. Regular thorough examination of the entire body during grooming facilitates identification of developing lesions.

Common symptoms and presentations of equine sarcoids vary by tumor type, with six recognized classifications having characteristic appearances. Occult sarcoids appear as circular areas of alopecia with roughened, slightly thickened skin, often mistaken for fungal infection. Verrucous sarcoids present as gray, warty, hyperkeratotic masses with irregular surfaces resembling cauliflower. Nodular sarcoids form firm, well-defined subcutaneous nodules that may be covered by normal skin or may ulcerate. Fibroblastic sarcoids are fleshy, often ulcerated masses that bleed easily and may grow rapidly following trauma. Mixed sarcoids combine features of multiple types. Malevolent sarcoids are rare aggressive forms showing invasive growth with satellite nodules and cording along lymphatics.

Behavioral changes associated with equine sarcoids often relate to irritation, discomfort, or interference with normal function depending on tumor location. Horses with sarcoids near the eyes may show head shyness or resistance to bridling. Girth-area sarcoids cause sensitivity during saddling and may lead to behavioral problems during riding. Sarcoids on the limbs may cause altered gait or reluctance to move if they interfere with joint movement or become traumatized. Sheath or udder sarcoids may cause behavioral changes during urination or handling of these areas. General irritability may accompany large or ulcerated sarcoids that attract flies and cause discomfort.

Physical signs of equine sarcoids are directly observable and vary with tumor type and stage. Size ranges from barely visible occult lesions to massive tumors several inches in diameter. Common locations include the paraorbital region, ears, muzzle, ventral abdomen, sheath, udder, axillary and inguinal regions, and areas of previous trauma. Multiple sarcoids frequently occur, with affected horses often developing numerous tumors over time. Ulceration and bleeding characterize fibroblastic types, attracting flies and creating hygiene concerns. Secondary infection may develop in ulcerated sarcoids. Regional lymph node enlargement occasionally accompanies aggressive tumor types.

Symptom progression in equine sarcoids follows variable patterns depending on tumor type and external influences. Some sarcoids remain stable for months to years, neither growing nor regressing significantly. Others grow progressively, particularly following trauma, surgical intervention, or inappropriate treatment attempts. Occult and verrucous sarcoids may transform to more aggressive fibroblastic types following irritation. Multiplication over time is common, with new sarcoids developing in addition to existing tumors. Seasonal variation occurs in some cases, with increased activity during fly season when irritation is greater. Malevolent sarcoids show continuous aggressive progression regardless of intervention.

Emergency symptoms directly related to sarcoids are uncommon but may occur in specific situations requiring veterinary attention. Profuse bleeding from traumatized fibroblastic sarcoids may require intervention, though life-threatening hemorrhage is rare. Sarcoids causing complete visual obstruction, airway compromise, or inability to eat or drink warrant urgent evaluation. Severe secondary infection with systemic signs of illness requires treatment. Rapid enlargement over days suggesting transformation or secondary complications needs assessment. While sarcoids rarely constitute true emergencies, concerning developments should prompt timely veterinary consultation.

Physical examination provides the foundation for sarcoid diagnosis, with experienced veterinarians often able to make presumptive diagnosis based on characteristic clinical appearance and location. Veterinarians assess lesion type, size, number, location, and relationship to surrounding tissues. Documentation through photography establishes baseline for monitoring progression or response to treatment. Examination of regional lymph nodes evaluates for evidence of aggressive or malevolent behavior. Assessment of lesion relationship to functional structures including eyes, mouth, sheath, and tack contact areas guides treatment priority. Complete skin examination identifies all lesions, as multiple sarcoids commonly coexist.

Diagnostic tests for sarcoid confirmation include biopsy for histopathology, the gold standard for definitive diagnosis. Tissue sampling through excisional or incisional biopsy provides material for microscopic examination revealing characteristic histological features. Histopathology shows fibroblastic proliferation with distinctive growth patterns and often identifies viral-induced cellular changes. Biopsy also rules out other tumor types that may mimic sarcoid appearance. However, biopsy carries risk of stimulating sarcoid growth and worsening prognosis, so the decision to biopsy requires careful consideration. In many cases, clinical diagnosis based on appearance is sufficiently reliable to guide treatment without biopsy.

Advanced diagnostics may be employed in selected cases or for research purposes, though they are not routinely required for clinical management. Polymerase chain reaction testing detects BPV DNA within lesions, confirming viral presence, though this does not change clinical management. Immunohistochemistry may identify viral proteins or assess cellular markers. Advanced imaging including ultrasound or thermography may evaluate lesion extent and vascularity in some cases. Genetic testing for sarcoid susceptibility markers is not currently available clinically but represents an area of ongoing research. Complete blood count and biochemistry panels are not specifically diagnostic but may be performed to assess overall health before treatment.

Differential diagnosis for skin lesions potentially confused with sarcoids includes various neoplastic and non-neoplastic conditions. Squamous cell carcinoma may appear similar to some sarcoid presentations, particularly around the eyes and muzzle. Melanoma, common in gray horses, produces nodular skin masses requiring differentiation. Fibroma and other benign tumors may resemble nodular sarcoids. Granulation tissue, particularly at wound sites, may be confused with fibroblastic sarcoids. Fungal infections including dermatophytosis and phycomycosis produce skin changes potentially mimicking sarcoids. Warts caused by equine papillomavirus typically affect young horses and regress spontaneously, unlike sarcoids. Habronemiasis, summer sores, produces granulomatous lesions in similar locations. Accurate diagnosis through clinical evaluation and histopathology when indicated ensures appropriate treatment selection.

Emergency and immediate treatment for equine sarcoids is rarely necessary, as these tumors typically allow time for comprehensive evaluation and treatment planning. Acute hemorrhage from traumatized sarcoids may require pressure bandaging, cautery, or local hemostatic agents. Secondary infections complicating sarcoids may need antibiotic therapy and wound care. Pain management may be appropriate for large, ulcerated, or strategically located lesions causing discomfort. In most cases, treatment proceeds on an elective basis following thorough assessment and consideration of treatment options. Benign neglect may be appropriate for small, stable sarcoids in non-problematic locations.

Medical management options for equine sarcoids include topical and intralesional treatments that may be used alone or in combination with other modalities. Topical imiquimod, an immune response modifier, stimulates local antiviral and antitumor immunity. Topical 5-fluorouracil, a chemotherapy agent, inhibits DNA synthesis in rapidly dividing tumor cells. Intralesional cisplatin or bleomycin chemotherapy delivers high local drug concentrations directly to tumor tissue. Intralesional BCG immunotherapy stimulates immune responses against sarcoid cells. Topical acyclovir has been used based on viral etiology, though efficacy is variable. Medical treatments often require extended treatment courses with variable success rates.

Surgical options remain common sarcoid treatments despite well-documented recurrence risks. Conventional surgical excision involves cutting out sarcoids with margins, though achieving adequate margins is often difficult. Recurrence rates following surgery alone approach or exceed fifty percent for many sarcoid types. Laser ablation using carbon dioxide laser provides precise tissue removal with reduced hemorrhage and potentially reduced viral dissemination. Cryotherapy freezes sarcoid tissue, causing cell death, and may be used alone or combined with surgery. Radiofrequency hyperthermia raises tumor temperature to lethal levels. Ligation of pedunculated sarcoids restricts blood supply, causing necrosis. Surgical success depends heavily on sarcoid type, location, size, and treatment history.

Radiation therapy offers effective sarcoid treatment with lower recurrence rates than many other modalities but requires specialized facilities. Brachytherapy implants radioactive sources directly into or around sarcoids, delivering localized high-dose radiation. External beam radiation therapy applies radiation from outside sources but requires repeated treatments and specialized equipment. Radiotherapy is particularly valuable for periorbital sarcoids where surgical options are limited. Success rates exceeding eighty to ninety percent are reported for appropriately selected cases. Limited availability and cost restrict radiation therapy to referral settings for cases warranting intensive treatment.

Combined and adjunctive treatments often provide better outcomes than single modalities. Surgical reduction combined with adjunctive cisplatin or radiation therapy improves success for larger sarcoids. Immunotherapy following debulking may help prevent recurrence. Sequential treatments addressing initial response and subsequent development of new lesions may be necessary. Autologous vaccination using killed tumor tissue has shown promise in some studies. Integrative approaches tailoring multiple modalities to individual cases optimize outcomes. Treatment protocols should be developed in consultation with veterinarians experienced in sarcoid management.

Treatment decision factors influencing modality selection include sarcoid characteristics, location, previous treatment history, and practical considerations. Sarcoid type matters significantly, with occult and verrucous forms often responding well to simpler treatments while fibroblastic and malevolent types require more aggressive approaches. Location determines cosmetic and functional impact of treatment and influences recurrence visibility. Size affects treatment difficulty and required margins. Previous treatment, particularly previous surgical attempts, worsens prognosis substantially. Available facilities, expertise, and financial resources constrain treatment options. Owner expectations regarding outcome, treatment intensity, and acceptable risk inform decision-making.

Recovery timeline following sarcoid treatment varies considerably based on treatment modality, tumor characteristics, and individual healing response. Surgical sites typically heal within two to four weeks with appropriate wound care. Cryotherapy-treated areas develop eschar that sloughs over two to four weeks before healing. Chemotherapy-treated sarcoids regress over several weeks to months depending on initial response. Radiation therapy effects continue for weeks after treatment completion, with full response assessment delayed accordingly. Complete assessment of treatment success requires extended observation periods of three to six months or longer given delayed recurrence potential.

Post-treatment care and monitoring protocols address wound management, complication detection, and recurrence surveillance. Surgical site care includes appropriate bandaging when feasible, fly control, and infection prevention. Chemotherapy treatment sites may develop local reactions requiring management. Regular reassessment at scheduled intervals evaluates healing and screens for early recurrence. Photographic documentation enables objective comparison over time. Owner education regarding warning signs of recurrence empowers early detection. Long-term monitoring continues indefinitely given lifelong recurrence risk, with examination during routine veterinary visits.

Prognosis factors significantly influence expected outcomes following sarcoid treatment. Sarcoid type represents a primary determinant, with occult and verrucous forms having better prognoses than fibroblastic and malevolent types. Size matters, with smaller sarcoids responding better to treatment than larger tumors. Location affects both treatment options and recurrence detection. Treatment history dramatically influences prognosis, with untreated sarcoids having substantially better outcomes than previously treated recurrent tumors. Treatment modality selection appropriate to the specific case improves success rates. Complete initial treatment achieving tumor-free margins or complete destruction improves outcomes compared to incomplete treatment.

Long-term soundness outlook following successful sarcoid treatment varies based on treatment outcomes and ongoing vigilance. Many horses achieve lasting remission following appropriate treatment, returning to normal function and use. Recurrence risk persists indefinitely, requiring ongoing monitoring throughout the horse's life. New sarcoid development in horses with previous tumors is common and should be anticipated. Horses with treatment-responsive sarcoids may experience repeated cycles of treatment and remission. Quality of life considerations guide decisions regarding treatment intensity for persistent or recurrent disease. Some horses live comfortably with stable sarcoids managed conservatively rather than treated aggressively.

Management practices that reduce sarcoid risk focus on minimizing viral exposure, maintaining skin integrity, and managing genetic susceptibility through breeding decisions. Fly control measures reduce mechanical vector transmission of BPV between animals. Good wound management prevents skin breaks that might serve as viral entry points and reduces sarcoid development at injury sites. Avoiding trauma to existing skin lesions prevents transformation to more aggressive forms. Isolation of heavily affected horses may reduce viral reservoir exposure to susceptible animals. Hygiene practices including equipment sanitation may reduce fomite transmission, though this route is not well characterized.

Nutritional prevention recommendations focus on supporting immune function and skin health, though specific nutrients preventing sarcoid development have not been identified. Balanced nutrition meeting all equine requirements supports overall health and immune competence. Adequate protein supports tissue repair and immune function. Balanced vitamin and mineral supplementation addresses deficiencies without creating excesses. Omega fatty acid supplementation may support skin health and immune function. Antioxidant nutrients including vitamin E and selenium support cellular health. Overall nutritional adequacy contributes to disease resistance without specifically preventing sarcoid development.

Exercise and conditioning recommendations for sarcoid prevention are nonspecific, focusing on overall health maintenance. Regular appropriate exercise supports immune function and general wellbeing. Conditioning programs should avoid creating wounds or chronic irritation at sarcoid-prone locations. Tack fit and equipment management prevent chronic trauma that might increase sarcoid risk at contact points. Exercise maintaining fitness without excessive stress supports immune competence. Appropriate activity levels throughout life contribute to overall health and disease resistance.

Environmental factors affecting sarcoid risk include fly populations, facility management, and contact with potentially infected animals. Aggressive fly control programs reduce vector-mediated transmission. Stable management minimizing fly breeding habitat supports fly control efforts. Facility design reducing fly access protects horses during housing. Pasture management may reduce fly populations in outdoor environments. Geographic considerations regarding endemic BPV prevalence may influence location decisions for highly susceptible horses. Minimizing contact between cattle and susceptible horses may reduce cross-species transmission, though this relationship requires further study.

Breeding recommendations address the hereditary component of sarcoid susceptibility. Breeding from heavily affected horses perpetuates genetic susceptibility in offspring. Selection against breeding horses with multiple sarcoids or strong family histories may reduce population susceptibility over time. Informed breeding decisions consider sarcoid history alongside other desirable and undesirable traits. Genetic testing for susceptibility markers, when available, could inform breeding decisions. Currently, phenotypic assessment of sarcoid history remains the practical approach to considering this factor in breeding programs.

Daily management adjustments for horses with sarcoids depend on tumor location, type, number, and treatment status. Grooming routines should avoid traumatizing sarcoids while maintaining overall coat care. Fly control measures protect exposed or ulcerated sarcoids from irritation and contamination. Monitoring sarcoid appearance for changes in size, character, or behavior enables early detection of concerning developments. Wound care protocols maintain hygiene for ulcerated lesions. Medication application follows prescribed schedules for horses receiving topical or systemic treatments. Documentation through regular photography tracks progression or response to treatment.

Housing and turnout considerations address sarcoid protection and fly exposure management. Fly sheets and masks protect sarcoid-prone areas and reduce irritation of existing tumors. Housing during peak fly activity times reduces vector exposure. Facility maintenance minimizes fly breeding habitat. Turnout timing may be adjusted to avoid peak fly hours in heavily affected horses. Clean, dry environments reduce contamination risk for ulcerated sarcoids. Companion horse selection considers avoiding trauma to sarcoid-bearing horses from herd interactions.

Exercise modifications depend on sarcoid location and interference with normal function or equipment. Sarcoids in tack contact areas may require equipment modifications, padding, or alternative tack placement. Limb sarcoids affecting movement may necessitate reduced activity levels. Large or ulcerated sarcoids may require exercise reduction during treatment phases. Horses with periorbital sarcoids may need protective equipment during riding. Return to normal activity follows successful treatment once healing permits. Most horses with sarcoids continue normal work with appropriate accommodations.

Monitoring and ongoing care requirements include regular assessment of sarcoid status and overall skin health. All sarcoids should be regularly evaluated for size changes, appearance changes, or development of new characteristics. New lesion development should be noted and brought to veterinary attention. Measurement and photographic documentation enables objective tracking over time. Post-treatment monitoring watches for recurrence at treated sites and development of new tumors elsewhere. Lifelong vigilance is appropriate given persistent recurrence and new development risk. Annual or more frequent veterinary skin examinations supplement owner monitoring.

Quality of life and use considerations guide management decisions for horses with sarcoids. Many horses with sarcoids enjoy excellent quality of life and normal function with appropriate management. Cosmetic impact, while concerning to owners, does not affect the horse's wellbeing directly. Functional impact varies from minimal to significant depending on tumor characteristics and location. Treatment decisions balance potential benefits against risks and costs. Aggressive treatment may be appropriate for sarcoids threatening function while conservative management suits stable cosmetic lesions. Some horses live comfortably with managed sarcoid disease indefinitely. Severe, progressive, or treatment-refractory disease occasionally warrants consideration of euthanasia when quality of life cannot be maintained.

High-risk breeds for equine sarcoids have been identified through epidemiological studies, though susceptibility exists across all breeds. Quarter Horses and Appaloosas appear overrepresented in some studies, potentially related to shared genetic backgrounds. Arabian horses have been identified as having elevated risk in certain populations. Thoroughbreds show variable risk depending on study population and geographic location. Various warmblood breeds appear in sarcoid case series, though specific breed associations vary. The genetic basis of susceptibility relates to immune system genes, particularly MHC class II alleles, that influence response to BPV infection. Breed associations may reflect population frequencies of susceptibility alleles rather than breed-specific factors per se.

Use and discipline considerations do not directly influence sarcoid development, though they may affect detection, impact, and treatment priority. Show horses face greater impact from cosmetically concerning sarcoids that might affect presentation. Performance horses may experience functional limitations from strategically located tumors. Horses in regular work and veterinary care may have sarcoids detected earlier than horses receiving less frequent attention. Breeding animals warrant particular consideration regarding perpetuating genetic susceptibility through reproduction. All horses regardless of use benefit from regular skin examination and appropriate management of detected sarcoids.

Genetic testing and breeding recommendations address the hereditary susceptibility component of sarcoid development. While specific genetic tests for sarcoid susceptibility are not currently available commercially, research has identified associated MHC alleles. Breeding decisions should consider sarcoid history, avoiding reproduction of heavily affected animals when alternatives exist. Offspring of affected horses warrant closer monitoring for sarcoid development. Breed organizations might consider sarcoid susceptibility in breeding recommendations alongside other health concerns. As understanding of genetic factors advances, more specific breeding guidance may become possible. Currently, phenotypic assessment based on individual and family sarcoid history guides breeding considerations.

Commonly co-occurring conditions with equine sarcoids include other skin conditions and situations that may complicate sarcoid management. Multiple sarcoid types commonly coexist on the same horse, requiring assessment and treatment of each lesion. Secondary bacterial infection may complicate ulcerated or traumatized sarcoids, requiring concurrent antibiotic therapy. Fly strike and myiasis may affect exposed sarcoid lesions, particularly during warm seasons. Proud flesh formation may accompany healing of surgically treated sarcoid sites. Immune system abnormalities, whether primary or related to concurrent disease, may influence sarcoid behavior and treatment response. Other skin tumors including squamous cell carcinoma or melanoma may occur concurrently in the same horse.

Conditions with similar symptoms requiring differentiation from equine sarcoids include various skin tumors and non-neoplastic lesions. Squamous cell carcinoma, particularly around the eyes and muzzle, may mimic sarcoid appearance and occurs in similar locations. Melanoma in gray horses produces pigmented nodules requiring distinction from nodular sarcoids. Fibroma and other benign tumors resemble certain sarcoid types. Equine papillomavirus warts affect young horses and differ from sarcoids in behavior and prognosis. Summer sores from Habronema species cause granulomatous lesions at similar locations. Pythiosis and other fungal infections produce proliferative lesions mimicking fibroblastic sarcoids. Exuberant granulation tissue at wound sites may resemble sarcoid tissue. Accurate diagnosis ensures appropriate treatment selection.

Potential complications of equine sarcoids include local effects of tumor growth and consequences of treatment attempts. Transformation of occult or verrucous sarcoids to more aggressive fibroblastic types commonly follows trauma or inappropriate treatment. Recurrence following treatment is common and may produce more aggressive tumors than the original. Self-trauma from irritation may worsen existing sarcoids. Secondary infection complicates ulcerated lesions and may delay healing following treatment. Scarring following treatment may affect cosmesis and function. Malevolent transformation with invasive growth and lymphatic spread represents the most serious progression, though this is relatively rare. Treatment complications vary by modality and may include local tissue damage, infection, or treatment reaction.