ALK positive anaplastic large cell lymphoma is a T-cell lymphoma usually 
occurring in children and young adults. It frequently involves lymph nodes and 
extranodal sites and is associated with favorable prognosis. A 20-year old man 
was admitted for painful mass in the left axilla with overlying skin redness. 
Clinical presentation and US findings were highly suspicious for sarcoma. 
Definitive diagnosis was established cytolologically and using ancillary 
technologies from cytological samples. Fine needle aspiration cytology of tumor 
mass (lymph node conglomerate and surrounding tissue) show predominance of 
large, pleomorphic, atypical cells with large nuclei and vacuolised cytoplasm. 
Atypical cells immunocytochemically were positive for LCA, CD30, CD3, EMA, and 
ALK; negative for CD15 and CD56. NPM-ALK transcript was detected by reverse 
transcriptase-polymerase chain reaction (RT-PCT). Molecular analysis of TCRß and 
TCRγ genes demonstrated clonal TCR genes rearrangement. Complex karyotype with 
multiple numerical and structural changes was found on conventional 
cytogenetics. These findings excluded sarcoma and corroborated the diagnosis of 
ALK positive ALCL. Cutaneous involvement in ALCL can clinically mimic sarcoma, 
especially in cases with localized disease without B symptoms. In those cases, 
immunostaining, PCR, and conventional cytogenetics are helpful to exclude 
sarcoma. Diagn. Cytopathol. 2017;45:51-54. © 2016 Wiley Periodicals, Inc.