Small cell variant of anaplastic large cell lymphoma presenting as arm mass in a child: a rare entity with diagnostic challenge.

Anaplastic lymphoma kinase positive, anaplastic large cell lymphoma (ALCL) is an uncommon T-cell non-Hodgkin lymphoma. A rare morphological variant-small cell variant of ALCL may pose diagnostic challenge especially when it presents primarily as a soft tissue mass. We present a rare case of small cell variant of ALCL in a 14-year-old female presented with arm swelling with emphasis on clinical, morphological and immunohistochemical aspects. Pathologists should be aware of this entity when considering a differential diagnosis of malignant round cell tumor as early and correct diagnosis has important clinical implications.