Epithelioid hemangioendothelioma (EHE) involving pleural effusion

A 63-year-old male presented with significant bilateral pleural effusions. The cytopathological evaluation of the pleural effusion fluid on cellblock preparations and ThinPrep was positive for scattered single polygonal cells and clusters of epithelioid cells in a background of mesothelial cells and lymphocytes. The epithelioid cells had ample cytoplasm with mildly to moderately enlarged nuclei, mildly coarse chromatin, and occasional prominent nucleoli. The key distinguishing cytomorphological feature was the intracytoplasmic vacuoles, some containing red blood cells (Figures 1 and 2). Review of the patient's medical history revealed a diagnosis of epithelioid hemangioendothelioma (EHE) 7 years prior. He had a distal fibular cortex mass associated with periosteal reaction and less severe bilateral pleural effusions. Histological evaluation of a core biopsy and the subsequently resected surgical specimen revealed a 1.8 cm mass composed of similar cells as in the current pleural effusion, which led to a diagnosis of EHE (Figure 3). Five years after the initial diagnosis, the patient presented with back pain. A PET/CT scan showed multiple subcentimeter pulmonary nodules and a lytic lesion of vertebral bone, confirmed by biopsy to be metastatic EHE. Immunohistochemical stains of the cellblock of the current pleural effusion revealed that the neoplastic cells were diffusely and strongly positive for CAMTA1 (both nuclear and cytoplasmic) (Figure 4A), ERG (nuclear) (Figure 4B), and CD31, supporting the diagnosis of EHE. Calretinin highlighted background mesothelial cells (Figure 4C). The patient was treated with radiation, but died 10 years following the initial diagnosis.