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. The disease is granular cell tumor (Monarch Disease Ontology id MONDO_0006235). Also known as: Abrikossoff tumor, Abrikossoff tumour, Abrikossoff's tumor, Abrikossoff's tumour, granular cell myoblastoma, granular cell neoplasm, granular cell nerve sheath tumor, granular cell nerve sheath tumour.