Basal cell carcinomas in association with basaloid follicular hamartoma

We describe a unique case of various types of basal cell carcinoma (BCC) associated with basaloid follicular hamartoma (BFH) in a 56-year-old female patient. The lesion consisted of a dark brown and elastic soft nodule and papules within the area of a birthmark on the neck. The lesion was surgically excised. Histological examination of the nodular region revealed aggregations of neoplastic basaloid cells. We diagnosed the nodule as BCC with a racemiform or reticular pattern. In addition, a specimen taken from brownish black papules within the birthmark was found to be composed of anastomosing cords of basaloid cells accompanied by infundibular cystic structures. These features were consistent with an infundibulocystic BCC. In contrast, specimens from a hamartomatous plaque showed distinctive branching strands of basaloid cells that are suggestive of BFH. Therefore, our findings indicate that several types of BCC may develop within a BFH.