Happle-Tinschert syndrome variable phenotype as part of the mosaic hedgehog spectrum: Report of three cases.

Happle-Tinschert syndrome is a rare genodermatosis caused by a postzygotic mutation in SMO gene. The most recognized clinical findings include segmentally arranged basaloid follicular hamartomas, nevoid hypertrichosis, linear atrophoderma, and hypopigmentation or hyperpigmentation following Blaschko lines associated with osseous, dental, and cerebral alterations. We report three additional cases, two of which lacked the pathognomonic basaloid follicular hamartomas, with genetic confirmation and detailed clinical characterization and describe new cutaneous features of this infrequent syndrome.

Cutaneous inflammation as a marker of malignant transformation in a patient with linear unilateral basaloid follicular hamartoma.

Basaloid follicular hamartoma is a rare, benign and superficial malformation of hair follicles, characterized histologically by epithelial proliferation of basaloid cells with radial disposition. It can be mistaken for basal cell carcinoma. Even though these hamartomas are considered benign lesions, malignant transformation has rarely been reported. We report the case of a 45-year-old healthy woman, with linear, unilateral basaloid follicular hamartoma which developed inflamed papules histologically suggestive of basal cell carcinoma. We believe that identification of local inflammation could be a clinical clue to guide us towards a malignant transformation of basaloid follicular hamartoma.