부산대학교 도서관

Background: Hibernoma is a rare benign tumor derived from brown adipose tissue. Little information is available regarding its cytologic features, although its histopathology and ultrastructure have been well described.Case: A 63-year-old woman presented with a mass in her left scapular region. A core-needle imprint cytology of the mass suggested a diagnosis of hibernoma, and the mass was extirpated. At the time of surgery, the mass was well-defined, soft, yellowish-brown, 8 × 8 × 3cm in size, and located in the subcutaneous fatty tissue.An imprint cytology showed clusters of large round to polygonal cells often superimposed with delicate capillaries. The tumor cells were classified into 3 main types: those with fine granular cytoplasm, multivacuolated cytoplasm, and univacuolated cytoplasm.Pigment granules were occasionally found in the cytoplasm. The nuclei were small and round to oval with a small nucleolus. The histological sections displayed the typical features of hibernoma and were stained positive with the Sudan III stain.Ultrastructurally, numerous mitochondria and a varying number of lipid droplets were observed in the cytoplasm.Conclusion: Hibernomas can be diagnosed by cytology based on the presence of the tumor's three characteristic cell types and the presence of occasional pigment granules. Imprint cytology may be useful for the diagnosis of this tumor.