Arezoo Eftekhar-Javadi - Department of Pathology, Tehran University of Medical Sciences, Tehran, Iran
Dorna Motevalli - Department of Pathology, Tehran University of Medical Sciences, Tehran, Iran
Hedieh Moradi-Tabriz - Department of Pathology, Tehran University of Medical Sciences, Tehran, Iran

Background: Well-differentiated liposarcoma (WDL)/atypical lipomatous tumor is the most frequent type of liposarcoma which can occur in the soft tissues of the body. These tumors nearly always develop in adults and no gender predilection is seen and have tendency to recur. Rare cases of WDL/ALT has been reported in English language literature. Herein, we report a rare case of WDL/ALT in a 1 year old boy.Case presentation: A one-year-old boy was brought to Sina hospital with a slow-growing right shoulder mass suspicious for arteriovenous malformation. The patient was otherwise normal. The lesion was resected completely. The specimen sent to pathology ward. Grossly, it was an encapsulated grayish mass measuring 18*12*7 cm with elastic consistency. Cut sections showed tan homogenous surface areas. Microscopically neoplastic tissue composed of mature adipose cells making lobules separated by fibrous and collagenous bundles containing spindle cells showing atypical enlarged pleomorphic and hyperchromatic nuclei some with prominent nucleoli and scattered mast cells. Foci of myxoid changes are also noted. Immunohistochemical study showed positive MDM2.Discussion: Histomorphology and immunohistochemical study was in favour of well-differentiated liposarcoma (WDL)/atypical lipomatous tumor. Although the mentioned tumor is very rare in this age, this diagnosis should be considered in differential diagnosis. Our patient scheduled for close follow-up. Life-long follow-up is required as recurrence may be very late.

Well-differentiated liposarcoma, atypical lipomatous tumor