Fine-needle aspiration characteristics of hibernoma

BACKGROUND. Hibernoma is a rare, benign lipomatous tumor with features of b rown fat. The preoperative diagnosis of hibernoma is difficult at times bec ause its clinical, radiographic, and fine-needle aspiration (FNA) character istics overlap with those of liposarcoma. METHODS. The preoperative FNA findings of eight surgically excised hibernom as from seven patients [three men and four women, ages 24-60 years) were re viewed. The cytologic features were compared with the histologic features o f the corresponding surgical specimens as well as lipomatous tumors and oth er lesions that may cause confusion in the differential diagnosis. RESULTS. The FNA cytologic features of the hibernomas were found to corresp ond well with their histologic appearance. The FNA findings included small, round, brown fat-like cells with uniform, small cytoplasmic vacuoles and r egular, small, round nuclei; delicate branching capillaries; and variable n umbers of mature fat cells. CONCLUSIONS, The FNA cytologic features of hibernoma are characteristic and useful in the preoperative investigation of lipomatous tumors, particularl y with regard to excluding a diagnosis of liposarcoma. Cancer (Cancer Cytop athol) 2001;93:206-210. (C) 2001 American Cancer Society.