Basaloid follicular hamartoma: Solitary and multiple types

Background: Multiple skin tumors often show autosomal dominant inheritance; solitary neoplasms are typically nonhereditary. Objective: The purpose of this study was to investigate a possible hereditary pattern in patients with multiple and solitary basaloid follicular hamartomas. Methods: Four new familial cases of multiple basaloid follicular hamartomas and 56 solitary nonhereditary examples were identified and their inheritance pattern recorded. Results: Clinically, basaloid follicular hamartomas were typically 1 to 2 mm, smooth facial papules. Histologically, they were well-circumscribed lesions composed of anastomosing strands of squamoid and basaloid cells in a loose stroma. Horn cysts and pigmentation were common. No significant association with other cutaneous or internal disease was found. Conclusion: Basaloid follicular hamartoma, a unique benign follicular tumor, was often diagnosed previously as trichoepithelioma or basal cell carcinoma. It is another cutaneous neoplasm in which patients with multiple lesions show autosomal dominant inheritance, whereas solitary growths with identical clinical, microscopic, and biologic features are nonhereditary.