Ultrasound-guided fine-needle aspiration of a posterior neck dedifferentiated liposarcoma with MDM2 fluorescence in situ hybridization performed on a Pap-stained smear.

Head and neck liposarcomas, while rare, tend to be subcutaneous and well-differentiated. Dedifferentiated liposarcomas of the head and neck are exceedingly rare in the literature. We present a case of a dedifferentiated liposarcoma arising in the soft tissue of the posterior neck of an 86-year-old man and diagnosed by fine-needle aspiration. Aspirate smears showed a dual population of atypical lipomatous and spindled cells. MDM2 (murine double minute 2) amplification was demonstrated on a Pap-stained smear using fluorescence in situ hybridization (FISH). To the best of our knowledge, this is the first report of MDM2 FISH amplification in a liposarcoma performed on an aspirate smear.