Angiosarcoma: hiding in plain sight.

Angiosarcoma is a rare, aggressive soft-tissue sarcoma of endothelial origin that necessitates early recognition, diagnosis, and treatment. The most commonly reported presentation consists of violaceous patches and plaques on the head and neck of elderly white men, with fewer reports affecting patients with Skin of Color. Most cases of angiosarcoma are idiopathic and tend to recur locally with early metastasis, conferring a poor prognosis. We report a case of an 83-year-old Fitzpatrick skin type IV man who presented with a large violaceous-to-black mamillated plaque on the frontotemporal scalp that was clinically highly suggestive of cutaneous angiosarcoma. However, unrevealing histopathology complicated our diagnostic process and delayed management. Immunohistochemistry was invaluable in determining the diagnosis of angiosarcoma. Our case highlights the aggressive nature of cutaneous angiosarcoma, necessitating close clinicopathologic correlation to confirm the diagnosis and initiate treatment.

Asymptomatic CD34+ plaque on the scalp of a child.

Fibroblastic connective tissue nevus (FCTN) is a rare, benign dermal mesenchymal lesion of fibroblastic and myofibroblastic lineage. We report a case of a 2-year-old male who presented with an 18-month history of an erythematous, asymptomatic, unchanging dermal plaque on the right medial frontal scalp. A punch biopsy showed a disorderly, bland, dermal fibroblastic spindle cell proliferation extending to the superficial subcutis. It stained positive for CD34, and concern for dermatofibrosarcoma protuberans was raised. However, FISH was negative for PDGFB rearrangement, and the constellation of findings was most consistent with FCTN. This case underscores the importance of distinguishing CD34+ mesenchymal tumors for both dermatologists and dermatopathologists. As these represent a rather diverse group of lesions with different biological behaviors, a knowledge of the differential diagnosis of these entities is critical for proper patient management.

Sickle cell crisis presenting as livedo racemosa.

Sickle cell disease is a monogenic hemoglobinopathy that results in the abnormal production of hemoglobin S, which yields the characteristic sickle-shaped red blood cells. Sickle cell vaso-occlusive crisis is a painful complication of sickle cell disease caused by red blood cell entrapment within the microcirculation. The resulting tissue ischemia triggers a secondary inflammatory process involved in the pathogenesis of varying inflammatory skin conditions. Chronic leg ulcers are the most common skin presentation in sickle cell disease. A 58-year-old woman with sickle cell disease presented with systemic edematous plaques with the most notable involvement of her bilateral legs, which exhibited reticulated purpuric patches with central pallor. We report a case highlighting an unusual presentation of livedo racemosa as the presenting sign in a patient with sickle cell disease in vaso-occlusive crisis.

Linear IgA bullous dermatosis associated with immunotherapy.

Linear IgA bullous dermatosis (LABD) is a rare mucocutaneus blistering autoimmune disease caused by IgA autoantibodies. Its clinical manifestation can be indistinguishable from bullous pemphigoid (BP), a similar autoimmune bullous disease caused by IgG and IgE autoantibodies. Although BP has been reported as an adverse cutaneous effect of immunotherapy, LABD has rarely been associated with immunotherapy in the literature. We present the case of a 67-year-old woman with metastatic ovarian cancer receiving anti-PD1 and anti-CTLA4 with new onset pruritic tense bullae to the trunk, hands, elbows (in annular distribution) that occurred after immunotherapy. Skin biopsy showed subepidermal blister with abundant neutrophils on H&E histology, and linear IgA staining at the basement membrane on direct immunofluorescence consistent with the diagnosis of LABD. The condition did not improve on initial prednisone taper, but blisters rapidly resolved a few days after initiation of dapsone therapy. We favor that our patient's LABD is secondary to her immunotherapy. Our case highlights the importance of both H&E histology and direct immunofluorescence in diagnosis of blistering disorders in patients on immunotherapy to help in choosing the most effective treatment option in an attempt to avoid discontinuation of immunotherapy.