Trichofolliculoma with incidental focal acantholytic dyskeratosis

Incidental focal acantholytic dyskeratosis has been described in a variety of cutaneous lesions, including benign and malignant epithelial lesions, fibrohistiocytic lesions, inflammatory lesions, and melanocytic lesions. It has also been observed in follicular lesions such as comedones and ruptured follicles. We report the case of a 47-year-old man with a firm, flesh-colored 2-mm pruritic papule in the sun-exposed area above the left eyebrow. An excisional biopsy was performed, the tissue was processed, and the hematoxylin and eosin slides were evaluated. Microscopic examination showed a dilated cystic cavity filled with keratinous debris and scattered fragments of hair. Smaller secondary follicular structures branched from the primary cyst's walls into the adjacent dermis. Hyperkeratosis, acantholysis, dyskeratosis, and suprabasilar clefts were also focally present. Correlation of the lesion's clinical morphology and microscopic features established a diagnosis of trichofolliculoma with incidental focal acantholytic dyskeratosis. Hence, trichofolliculoma can be added to the list of follicular lesions in which focal acantholytic dyskeratosis may be observed as an incidental microscopic change.