As the name suggests, the histogenesis of the granular cell tumor is uncertain, but this intriguing neoplasm has occasioned much speculation and controversy since its description in 1926 as a myoblastoma. Though ubiquitous in its anatomic location, it is usually small, solitary, benign, and readily recognized by routine light microscopy, and questions concerning it are principally academic. However, a small number of cases are malignant and they can be difficult to identify in paraffin sections. The combined input from immunohistochemistry and electron microscopy has greatly clarified understanding of the morphology of this lesion and both methods are helpful when the differential diagnosis is a problem. The cell of origin is still undecided, and although distinct neural features argue for Schwannian origin, the noncommittal term granular cell tumor continues to be appropriate.

Granular cell tumor: a review of the pathology and histogenesis.

Seventeen cases of granular cell tumor (GCT) of the breast are reviewed. The demographics and clinical features are reviewed and the radiologic and pathologic features as well as the immunohistochemistry are discussed. To our knowledge, our series of 17 breast GCT cases represent the largest series published to date.

Granular Cell Tumor of the Breast: A Series of 17 Cases and Review of the Literature

Immunohistochemical demonstration of the lysosome-associated glycoprotein CD68 (KP-1) in granular cell tumors and schwannomas

https://www.annalsthoracicsurgery.org/article/S0003-4975(96)00443-2/pdf

Granular cell tumors of the esophagus: a clinical and pathologic study of 13 cases.

A rare subset of distinctive cutaneous nonneural granular cell tumors was described by LeBoit et al in 1991 and termed "primitive polypoid granular-cell tumor." Herein, we report our experience with 13 similar, distinctive nonneural granular cell tumors. Affected patients included 7 males and 6 females ranging in age from 5 to 83 years (mean, 25 years; median, 16 years). These cutaneous lesions involved the back (5 cases), neck, shoulder, thigh (2 cases each), chin, and elbow (1 case each). Clinically described as smooth, nontender cutaneous nodules, the tumors ranged in size from 0.2 to 2.8 cm (median, 0.8 cm) and were present from months to years before excision. Mitoses numbered from 1 to 6 per mm (median, 2). Eight of the lesions were polypoid, based in the papillary dermis with extension to the superficial dermis and associated with an epithelial collarette. Five of the lesions were situated deeper in the reticular dermis with limited extension into the subcutis but clinically were also nodular. All the tumors were well circumscribed and composed of spindled to ovoid cells with abundant granular, eosinophilic cytoplasm and vesicular nuclei with small prominent nucleoli. Immunohistochemistry revealed reactivity only for NKI-C3 (11 of 12 cases), CD68 (7 of 11 cases), and NSE (5 of 10 cases); S-100 protein as well as other melanocytic, epithelial, and myoid markers were uniformly negative. All 13 of the lesions were locally excised and in the 8 cases with adequate follow-up ranging from 13 to 126 months (mean, 68 months; median, 41 months), none has recurred locally. However, one tumor (case no. 11) gave rise to a local lymph node metastasis 25 months after presentation, but the patient is currently disease-free 70 months after lymphadenectomy. These cutaneous granular tumors do not appear to be neural or Schwannian in nature, but their precise line of differentiation is unknown.

Primitive nonneural granular cell tumors of skin: clinicopathologic analysis of 13 cases.

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.

Callihan

Papers

Granular cell tumor: A clinicopathologic study of 110 patients