NCIt definition : An unusual benign or malignant neoplasm characterized by the presence of neoplastic
large polygonal cells with granular, eosinophilic cytoplasm which contains abundant
lysosomes. It was originally thought to be a tumor originating from muscle cells and
was named granular cell myoblastoma. Subsequent studies have suggested a derivation
from Schwann cells. It affects females more often than males and it usually presents
as a solitary mass. A minority of patients have multiple tumors. It can arise from
many anatomic sites including the posterior pituitary gland, skin, oral cavity, esophagus,
stomach, heart, mediastinum, and breast.;