Solitary, multiple, benign, atypical, or malignant: the “Granular Cell Tumor” puzzle

The clinicopathologic features of 118 granular cell tumors (GCT) encountered at two affiliated hospitals were reviewed. A total of 110 patients were affected over this 32-year period of study (71 men, 39 women), and in 5% GCT were multiple. Patients ranged in age from 16 to 58 years (average 32 years) and were symptomatic for an average duration of 11 months prior to diagnosis. There was a greater than expected frequency of GCT among black patients (29%). Although tongue was the single most common anatomic site involved, relatively more GCT (44%) occurred in skin or subcutaneous tissue. Less common locations were breast parenchyma (10 cases), rectal mucosa and anus (6), vulva (4), esophagus and larynx (2 cases each). The correct preoperative diagnosis of this protean tumor was made in only three patients. GCT were surgically treated with the average diameter of resected tumor being 1.2 cm (range 0.2--3.5 cm). Pseudoepitheliomatous hyperplasia was noted in 11 tumors and in one vulvar GCT there was overlying in situ squamous cell carcinoma. Tumors were incompletely excised in 24 of 56 patients having adequate followup; only five of these 24 patients experienced a local recurrence of tumor. Malignant behavior was not observed. Results of histochemical and ultrastructural study are briefly discussed. The precise histogenesis of GCT is uncertain but Schwann cell origin is favored in most cases.

Pleomorphic adenoma (PA) is the commonest benign neoplasm of salivary glands.(1) PA can undergo malignant transformation to ex-pleomorphic adenoma (2,3) but rarely, can metastasise without malignant transformation.(4,5) Metastasising pleomorphic adenoma (MPA) is a rare malignant tumour which, histologically, is indistinguishable from PA yet produces secondary tumours in distant sites.(6,7,8) OBJECTIVE: Our aim is to review the literature for all reported cases of MPA and create a virtual series. The age and location of primary tumour with the location and time to metastasise will be reviewed. The prognosis and treatment options will be explored.