Abstract

Intravascular histiocytosis (IVH) is a rare benign condition characterized by poorly demarcated erythematous plaques often seen in the elderly. Historically, it has been associated with rheumatoid arthritis, trauma, and orthopedic interventions. Given its remarkable clinical presentation, there is often concern for aggressive underlying processes such as angiosarcoma. We present three recent consultation cases to highlight the classic clinicopathologic features of a rare entity. In our series, all cases occurred in men at an average age of 73 years. Prior to the cutaneous eruption, 2/3 received ipsilateral orthopedic interventions (shoulder or knee arthroplasty, or open reduction with internal fixation); one had trauma to the ipsilateral extremity. Based on available data, the time to onset after the inciting event was highly variable (range: 2-12 years). Clinically, 2/3 reported rapid spread of erythematous plaques measuring >20cm, raising concern for diagnoses such as angiosarcoma, plasmacytoma or diffuse dermal angiomatosis. These eruptions were associated with pruritus (2/3). The contributors’ histologic differentials included papillary intralymphatic angioendothelioma, intravascular pyogenic granuloma, angiolymphoid hyperplasia with eosinophilia, benign vascular proliferation not otherwise specified, as well as intravascular histiocytosis. Histologically, all the cases had ectatic vessels with nodular, intravascular collections of histiocytes, admixed lymphocytes, and neutrophils. Immunohistochemical stains for PU.1, CD68, and/or CD31 highlighted the intravascular histiocytes. To summarize, through this series we hope to bring attention to a rare, benign diagnosis with an alarming clinical presentation.