Acquired Perforating Osteoma Cutis: A Rare Histopathological Diagnosis.

ABSTRACT: Perforating osteoma cutis is a benign proliferation of mature bone within the dermis and subcutaneous tissue of the skin with transepidermal elimination. Transepidermal elimination of bone is the hallmark of perforating osteoma cutis and is defined by the breaching of bone through the epidermis. Perforating osteoma cutis is exceptionally rare because only 6 cases have been recorded in the literature at the time of preparation of this report. In this report, we present the case of a 65-year-old female patient with a medical history of nonmelanoma skin cancer, hypertension, hyperlipidemia, and type II diabetes mellitus presented for evaluation of a skin lesion of the posterior lower left leg, which had been present for 1 year. Clinical and histopathologic findings were consistent with the diagnosis of acquired perforating osteoma cutis. Treatment with surgical removal by tangential biopsy has thus far proven to be both diagnostic and therapeutic because no recurrence has been noted as of 6 months.

Cutaneous Malignant Squamomelanocytic Tumor: A Case Report of a Rare Neoplasm.

ABSTRACT: Cutaneous squamomelanocytic tumor (SMT) is an exceedingly rare cutaneous malignancy characterized by the presence of both squamous cell carcinoma and malignant melanoma within a single tumor. SMT typically presents clinically as keratotic skin papulonodules, most commonly occurring on the face, scalp, or other sun-exposed areas of middle-aged to elderly White male patients. Owing to the rare nature of this tumor, the histogenesis and prognosis remain relatively unclear. Histopathological examination of the tangential biopsy revealed an invasive cutaneous malignancy consisting of 2 distinct yet closely associated atypical cell populations: (1) a population of atypical squamoid epithelial cells arranged in cords and keratin pearls and (2) a population consisting of atypical, spindled cells with fine melanin pigment arranged in confluent sheets. Both populations of atypical cells emanated in an invasive pattern from the underside of the overlying epidermis into the deep dermis. Squamomelanocytic tumors are among the rarer types of collision tumors between 2 malignant lesions as most are basomelanocytic. For most reported SMTs, the melanoma population comprises epithelioid cell morphology, whereas our tumor is composed of spindled cell morphology. In this article, we exemplify a unique case of SMT in an 87-year-old male patient.