clinical, macroscopic and histopathological findings of trichofolliculoma in a dog: a case report

Trichofolliculoma is a rare, benign cutaneous neoplasm in dogs, originating as a hamartoma from the pilosebaceous units, which include the hair follicle and its associated sebaceous glands. although the precise etiology of trichofolliculoma remains unidentified, it is hypothesized that aberrations in the development and differentiation of hair follicles contribute to the formation of this lesion. epidemiologically, this condition manifests in adult dogs irrespective of breed, gender, anatomical location, or age. clinically, trichofolliculomas typically present as solitary lesions, characterized by dome-shaped, firm papules or nodules. the hallmark of these lesions is the presence of a central and pore, which may exude kerato-base material—a mixture of keratin and sebum—or contain clusters of hair strands. histopathological examination is essential for definitive diagnosis. therapeutic management primarily involves surgical excision of the mass, ensuring complete removal and preventing recurrence. alternative treatments, such as cryotherapy and laser therapy, may also be employed in certain cases. a 9-year-old male pit bull was examined with a cutaneous mass located on the forelimb. following surgical excision with safe margins, the specimen was placed in a sample container with 10% buffered formalin and referred to an anatomical pathologist for evaluation. macroscopically, the subcutaneous tissue appeared tan-brown, exophytic, irregular, and soft, with evident keratin accumulation on the surface. the tissue underwent routine histopathological processing, including sectioning into 5-micrometer slices and staining with hematoxylin and eosin (h&e). microscopic examination revealed a keratin filled cyct and lined with benign squamous epithelium within the dermis. surrounding the cyst were numerous hair follicles and mature sebaceous glands of varying sizes. additionally, severe and diffuse plasmocytic infiltration was noted within the neoplasm. the tissue margins were free of neoplastic cells, indicating that surgical excision alone was sufficient for treatment. as clear, after 8 months, there is no sign of tumor recurrence. the prognosis for dogs with trichofolliculoma is generally excellent because this lesion is benign and usually does not recur after surgical intervention and complete removal.