Melanotic Neuroectodermal Tumor of Infancy

Definition

Biphasic pigmented neoplasm arising from the neural crest, typically involving the head and neck region of children usually age 1 year or younger

Biphasic proliferation lf small and large cells
- Small neuroblastic cells resemble those of neuroblastoma
  - Small dense nuclei with scant cytoplasm
- Large melanin pigmented epithelioid cells
  - Large vesicular nuclei with prominent nucleoli
Cells are set in a dense collagenous stroma
- Present as cords, poorly formed tubules, and clusters of cells
  - Clusters are frequently discohesive with an alveolar pattern
- Large and small cells may be in adjacent discrete nodules or mixed
  - Large cells frequently form an outer layer surrounding small cells
Tumor may be grossly circumscribed but is usually invasive
Over 90% occur during the first year of life
- May be present at birth
Over 90% occur in bones of the head and neck (see Clinical at left)
- Maxilla is most common site, followed by mandible and skull
- Most common peripheral site is epididymis
Over 90% are benign if entirely resected (see Clinical at left)

Florette K. Gray Hazard MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342