Abstract
Infundibulocytic basal cell carcinoma has been described as a rare variant of basal cell carcinoma (BCC). To properly categorize and describe histological features of this rare entity, we retrospectively studied 159 cases diagnosed either as a solitary basaloid follicular hamartoma or infundibulocystic BCC. Among the 159 patients, 102(64%) were female and 57(36%) were male. The age range from 18-93 years-old (mean 70.9). 149 lesions presented on the head and neck and the remaining were from chest, back, axilla and perineum. The growth was almost always described on the examination as a pearly pink/white papule. The clinical diagnosis included BCC (71%), sebaceous hyperplasia (13.2%), cyst (12.6%), nevus (6.3%), SCC (1.9%) and melanoma (1.9%). All lesions were acquired and had appeared within a few years of biopsy. None of the lesions were described to have scaling and there were no known recurrences within 3-7 years of follow up. Upon histological investigation, the described lesion shows a small well-circumscribed, anastomosing cords of basaloid cells with pink eosinophilic stroma. It almost always originates from the epidermis (84.6%), has duct-like structures (97.5%), apoptosis (84.9%), and keratinization (94.3%). The palisading cells that are, at times, present with the lesion are cuboidal rather than columnar. In conclusion, we believe this lesion neither represents a carcinoma nor a hamartoma. Compared to basaloid follicular hamartoma, it is not follicular centric, is not a congenital lesion and has shown no syndromic association. We propose the name infundibulocystic basaloid adenoma because of the benign clinical course of this entity.
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