A small round cell lesion in the neck of an 11-year-old child

Abstract

Small round cell lesions in the neck of a pediatric patient may involve a lymph node or present as an extra-nodal solid tumor. Various proliferative lymph node lesions include non-specific reactive hyperplasia, infectious mononucleosis, Castleman’s disease, Rosai-Dorfman disease, Langerhans cell histiocytosis and malignant lymphoma. Besides lymphomas, the other pediatric small round cell tumors (SRCT) of the neck can be a group of malignancies that include neuroblastoma, Ewing’s sarcoma, embryonal rhabdomyosarcoma, and metastasis from retinoblastoma and small cell undifferentiated carcinoma. These lesions are characterized both histologically and cytologically by predominantly small round to oval cells. Special morphological features characterizing these lesions are exclusive noncohesive cells and lymphoglandular bodies for non-Hodgkin lymphoma; rosette formation and filamentous background for neuroblastoma; nuclear molding, acinar formation and paranuclear blue inclusion for metastatic small cell undifferentiated carcinoma; glycogen vacuoles for Ewing’s sarcoma; and tadpole cells for embryonal rhabdomyosarcoma. However, the so called characteristic cytomorphologic features may not be obvious or may be observed in more than one SRCT. To solve the differential diagnostic problems, ancillary studies like cytochemistry, immunocytochemistry, ultrastructure, flow cytometry, cytogenetics and molecular techniques may be of help. The present case is that of a small round cell lesion of neck in an 11-year-old girl.