Basal Cell Carcinoma, Infundibulocystic

Tozawa and Ackerman (1987) described a novel clinicopathologic variant of basal cell carcinoma that they termed 'basal cell carcinoma with follicular differentiation.' Their report generated considerable controversy in the literature, mainly concerning the difference between this basal cell carcinoma with follicular differentiation and trichoepithelioma (601606). Walsh and Ackerman (1990) proposed the designation 'infundibulocystic basal cell carcinoma,' on the basis of the main histopathologic characteristics of the neoplasm. They stated that infundibulocystic basal cell carcinoma was found frequently in patients with nevoid basal cell carcinoma syndrome (109400), also called Gorlin syndrome. Further debate ensued as to whether infundibulocystic basal cell carcinoma is the same as basaloid follicular hamartoma (Brownstein, 1992). Requena et al. (1999) described 2 families in which several members had multiple infundibulocystic basal cell carcinomas. None of the patients had palmar pits or jaw cysts. The authors performed histopathologic studies on 42 cutaneous lesions from 5 patients. Infundibulocystic basal cell carcinoma was found in 39 lesions. This clinicopathologic variant of basal cell carcinoma consists of a relatively well-circumscribed basaloid neoplasm composed of buds and cords of neoplastic cells arranged in anastomosing fashion and with scant stroma. Some of the neoplastic cords contain tiny infundibular cysts filled by cornified cells with abundant melanin. Linkage analysis in 1 family demonstrated that the affected members shared the same haplotype, but loss of heterozygosity for D9S196 could not be demonstrated in 2 patients from whom tumor DNA was available. Therefore, a diagnosis of nevoid basal cell carcinoma syndrome could not be eliminated. However, Requena et al. (1999) concluded that multiple hereditary infundibulocystic basal cell carcinomas represent a distinctive genodermatosis different from multiple hereditary trichoepitheliomas and nevoid basal cell carcinoma syndrome.