Fine Needle Aspiration Cytology of Metastatic Alveolar Rhabdomyosarcoma Misinterpreted as Carcinoma: A Case Report

Kim, Hyun Jung; Lim, Sung Jik; Park, Kyeongmee

Abstract

Fine-needle aspiration cytology(FNAC) has been used extensively in the diagnosis of metastatic malignancies. However, metastatic soft tissue sarcomas are often overlooked, primarily due to the low frequency with which they occur. Here, we report a rare case of metastatic rhabdomyosarcoma in both cervical lymph nodes, which was detected by FNAC. A 45-year-old woman presented with anosmia, postnasal drip, and sneezing, symptoms which had persisted for 1 month. The patient was found to have a tumorous lesion at the upper portion of the mid-turbinate, with multiple enlarged cervical lymph nodes, and this lesion was examined closely at our facility. FNA cytology smears obtained from both cervical lymph nodes revealed a high degree of cellularity, and displayed cohesive clusters with gland-like spaces, as well as single isolated cells with abundant karyorrhectic debris. The tumor cells exhibited round to oval nuclei containing fine chromatin, occasional small nucleoli, and scanty cytoplasm, or a total lack of cytoplasm. Some of the tumor cells were arranged in multinucleated forms and abundant dense eosinophilic cytoplasms, reminiscent of a rhabdomyoblast. The histological findings of the lymph nodes revealed an outstanding sinusoidal infiltration and a prominent alveolar growth pattern, interspersed with occasional typical rhabdomyoblasts. The immunohistochemical results [desmin(+), myoglobin(+), myogenin (+), pan CK(-), synaptophysin(-), neuron specific enolase(-)] supported a confirmative diagnosis of alveolar rhabdomyosarcoma. Alveolar rhabdomyosarcoma is a representative sarcoma, which typically manifests with nodal metastasis and carcinoma-like clustering. The cytopathologist should remain alert upon encountering unusual morphology, so that the possibility of this condition, although somewhat remote, should not be dismissed or overlooked.