Epithelioid hemangioendothelioma (EHE) is a vascular tumor that can occur at many body sites, including bone, soft tissue, lung, and liver (1). Its diagnosis in effusions is rare (2). The histologic pattern is associated with molecular findings. Two main subtypes have been described: WWTR1-CAMTA and YAP-TFE3 subtypes. Cytological features of EHE in effusion cytology has been described in the literature. The challenge in effusion cytology is a broad differential diagnosis and often lack of architectural findings (3,4). In scant cytology specimens, typical blister cells may not be easily identified. Classic histopathology reveals cords and nests of large endothelial cells with eosinophilic cytoplasm embedded in the background of myxohyaline stroma. Some cells may contain intracytoplasmic erythrocytes within vacuoles (primitive lumina). Cytologically, the cells are dispersed singly or present in clusters. The cellular morphology is predominantly epithelioid. Nuclei exhibit mild pleomorphism with occasional grooves and pseudoinclusions. Higher-grade tumors may have irregular nuclear membranes and prominent nucleoli. The background of blood and myxohyaline stroma can be appreciated in fine needle aspiration specimens (FNA). Intracytoplasmic lumens are identified in 82% of the cases (blister cells) with intracytoplasmic red blood cells present in almost half of the cases (5). The tumors with YAP-TFE3 translocation show different morphological features with predominantly solid or pseudoalveolar growth of epithelioid cells embedded in the fibrous stroma. Tumor cells can form vascular spaces. Intracytoplasmic vacuoles and intracytoplasmic red blood cells are rare. Cytologic features of this molecular subtype are similar to the classic subtype; however, the background of hyaline and myxoid stroma is not present. Predominantly the cells are eosinophilic with ample cytoplasm and mild nuclear pleomorphism (6). Up to 10% of these tumors exhibit frank malignant features with increased mitotic activity, necrosis, and solid growth pattern. These tumors resemble epithelioid angiosarcoma and have more aggressive clinical behavior (7,8). Ancillary testing (Immunohistochemistry and Molecular Testing) of the neoplastic cells in epithelioid hemangioendothelioma are positive for CD31, ERG1, podoplanin (D2-40), and FLI1 by immunohistochemistry. FISH testing can be performed to investigate the presence of WWTR1-CAMTA or YAP1-TFE3 rearrangements. Immunohistochemistry can also be used as a surrogate; nuclear staining for CAMTA1 is positive in the WWTR1-CAMTA1 subtype (9) and TFE3 is positive in YAP1-TFE3 rearranged tumors (10). In terms of prognosis, most tumors locally recur and about 20-30% of cases metastasize. High-risk features include marked nuclear atypia, solid growth pattern, necrosis, and presence of greater than 3 mitoses per 10 high power fields. Some studies reported that tumor size over 3 cm is a high risk factor (7). However, clear morphologic criteria to categorize more or less favorable variants are missing (8). In conclusion, though rarely diagnosed in effusions, it is important to recognize epithelioid hemangioendothelioma in the serous effusion may be the first sign of the disease or an indication of recurrent disease.