Subepidermal calcified nodule presenting as a cutaneous horn: two cases and a review of the literature.

Subepidermal calcified nodules are an uncommon subtype of idiopathic calcinosis cutis. Morphologically, this entity typically present as a single, well-circumscribed, white-yellow nodule. Based on clinical appearance alone, subepidermal calcified nodules are frequently misdiagnosed and often requires histological confirmation. We describe two cases of subepidermal calcified nodules presenting atypically as cutaneous horns. Subepidermal calcified nodules presenting as a cutaneous horn has rarely been reported; on review, there are fewer than 10 such cases have been described within the past 30 years. The cases described here illustrate the clinical variety and should increase awareness of subepidermal calcified nodules presented.

CD5+ Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type, Presenting as an Asymptomatic Nodule.

Primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), is a rare and aggressive variant of primary cutaneous lymphoma that typically expresses B cells as well as MUM1/IRF4, BCL2, and FOXP1, whereas BCL6 may be present or undetectable. We present a case of CD5+ PCDLBCL-LT presenting as a 6 mm pink-bluish nodule on the mid-left thigh, which was concerning for basal cell carcinoma. The histological examination reveals the presence of an intradermal proliferation of large, atypical CD5+, CD20+ BCL2+, BCL6+, MUM-1+, and Cyclin-D1+ lymphocytes in a nodular, diffuse interstitial and perivascular distribution. Because the patient presented with a small, single nodule, the systemic treatment of multiagent chemotherapy was avoided and localized electron beam radiation therapy with rituximab was initiated instead, achieving complete response. Early identification of PCDLBCL-LT is key for maximal therapeutic benefit and prognosis; it is important to consider PCDLBCL-LT on the differential when evaluating small, single nodules on the lower extremities of elderly patients.