A 52-year-old man was examined for an ulcerated, rapidly growing reddish nodule. It was 5.5 cm high with an 11 x 6-cm base and located on the left clavicle. The lesion had been present for approximately 7 years, and the patient complained occasional burning and pain. Clinical differential diagnoses included cutaneous lymphoma, sarcoma, squamous cell carcinoma, and cutaneous metastasis. Histopathologic examination revealed a well-circumscribed tumor involving the whole dermis and the subcutis and composed of partially confluent aggregates of matrical cells admixed with eosinophilic cornified material containing shadow cells. In addition, multinucleated giant cells, areas of calcification and metaplastic ossification, edema, and hemorrhage were also observed. On the basis of histopathologic features, the diagnosis of pilomatricoma was made. Our report highlights an unusual clinical appearance of pilomatricoma that made us consider a variety of primary or secondary cutaneous neoplasms in its differential diagnosis.

Am J Dermatopathol. 2007 Jun;29(3):286-9                                                                         © 2007 Lippincott Williams & Wilkins, Inc.