A Painless Right Supraclavicular Mass

An otherwise healthy, asymptomaticman in his 30s presented with a5-weekhistoryof apainless right supraclavicularmass. There was no history of trauma, recent infection, travel, or contacts with individuals whowere ill. He never smoked andwas a social drinker. There was no history of radiation therapy. Physical examination revealed a soft, nontender, semimobile mass in the right supraclavicular region measuring 5 × 6 cm. No cervical lymphadenopathy was detectable. Findings from flexible nasopharyngolaryngoscopy was normal. Fine-needle aspiration showed numerous dissociated cells with slightly irregular nuclei. A number of them possessed vacuolated cytoplasm. This was suggestive of a neoplasm, possibly liposarcoma (Figure, A). Computed tomographic (CT) imaging revealed a well-defined, 5.2 × 6.0 × 3.0-cm heterogeneous lesion with areas near fat density in the base of the right side of the neck clearly surrounded by a fat plane (Figure, B). Results from CT imaging of the chest, abdomen, and pelvis were negative for malignant disease. The patient underwent excisional biopsy of themass and neck dissection. The lesionwas identified immediately after raising subplatysmal flaps. It expanded partially into levels III and IV and separated easily from the prevertebral and paraspinal muscles. Grossexaminationshowedawell-circumscribedmasswithmyxoid cut surfaces streakedwith yellowdiscolorations (Figure, C).Microscopicexaminationrevealedamyxoidmultilobulatedtumorcomposed of nests of vacuolated lipoblast-like cells in a background of myxoid and chondromyxoid stroma framed by a delicate capillary network (Figure, D). The tumor cells were positive only for vimentin, a marker for soft tissue. Lymph nodes from levels II through V were negative for malignant disease. What is your diagnosis? 1