Infundibulocystic basal cell carcinoma also should be differentiated from basaloid follicular hamartoma. Basaloid follicular hamartoma is a rare follicular malformation with distinctive histopathologic features. It was originally described by Brown et al22 in 1969 as multiple papules in nasolabial folds associated with myasthenia gravis and diffuse alopecia. Since then, several cases have been reported, and now it is evident that basaloid follicular hamartoma may assume the following 5 different clinical forms: (1) an acquired generalized type, associated with myasthenia gravis and diffuse alopecia22- 24; (2) a congenital generalized type, associated with diffuse alopecia and cystic fibrosis25; (3) a generalized familial type, without any apparent associated disease26; (4) a localized linear and unilateral type27- 29 (Figure 11); and (5) a localized and solitary type that mimics a plaque of alopecia on the scalp27 or appears as an indurated papular plaque.30- 34 In our opinion, some of the cases reported as basaloid follicular hamartoma are better interpreted as trichoepitheliomas,35- 37 basal cell carcinoma of fibroepithelioma (Pinkus) type,38 or infundibulocystic basal cell carcinomas.11,39 Conversely, some cases reported as trichoepitheliomas are in our opinion examples of basaloid follicular hamartomas.40,41 Finally, some patients with myasthenia gravis seem to have multiple trichoepitheliomas and basaloid follicular hamartomas,23 supporting the notion that multiple follicular neoplasms and hamartomas may be cutaneous markers of a more complex familial syndrome. Table 1 summarizes the literature review and our interpretation of the reported cases of basaloid follicular hamartoma, multiple trichoepitheliomas associated with alopecia and myasthenia gravis, and infundibulocystic basal carcinoma. From the histopathologic point of view, basaloid follicular hamartoma is characteristic, and the lesion consists of malformed and distorted hair follicles composed of cords and strands of basaloid cells arranged in radial and anastomosing fashion (Figure 12). In contrast to trichoepithelioma, the stroma of basaloid follicular hamartoma is scant or absent, and when present it consists of eosinophilic compact collagen bundles with no fibrocytes. No follicular bulbs and papillae are seen in basaloid follicular hamartoma. Unlike infundibulocystic basal cell carcinoma, basaloid follicular hamartoma is a superficial malformation of hair follicles, and basaloid cords and strands are seen only at the sites where normal follicles should be present, with no proliferations of basaloid neoplastic aggregations in interfollicular dermis and no involvement of deeper reticular dermis. In brief, basaloid follicular hamartoma consists of malformed hair follicles, whereas infundibulocystic basal cell carcinoma is a malignant neoplasm composed of aggregations of neoplastic cells that involve and destroy preexisting hair follicles and interfollicular dermis, and sometimes infiltrate deeper dermis, subcutaneous fat, and skeletal muscle.