Granular cell tumor

The granular cell tumor ( Granularzellmyoblastom, Myoblastenmyom, Abrikossow tumor) is a rare benign tumor nichtepithelialer probably neuroectodermal origin, usually manifests in middle age. Main sites are the tongue, and skin and subcutaneous tissue of the trunk of the body. In addition, the tumor can occur at virtually any anatomic site. Clinically, it is a slow-growing, usually painless tumor which rarely recur after surgical removal. Malignant degeneration is observed in a small percentage of cases.

History

The first description of Granularzelltumors was made in 1926 by Alexei Ivanovich Abrikossow, who initially interpreted the lesion as a benign neoplasm of striated skeletal muscle and covered with the name Myoblastenmyom.

Etiology

The causes underlying the granular cell are unknown. As a likely starting point for the development of tumors is considered the Schwann cell, but a relationship can not be established in all cases. The rare congenital variant of the gingival Granularzelltumors is possibly a non -neoplastic reactive lesion.

Epidemiology

The peak age of disease is in middle age, but the onset time varied within wide limits. Women are affected slightly more often than men.

Pathology

Macroscopically, it is usually small, usually less than 3 cm measured off-white, pale yellow or cream-colored, often poorly demarcated tumors of firm consistence, preferably in the tongue (40 %) and skin and subcutaneous tissue in particular the trunk of the body (30%). occur In addition, granular cell tumors have been described in many other locations, including bronchial (13%), urinary and genital organs (13%), gastrointestinal tract ( 6%) or central nervous system.

Intracranial tumor occurs mainly in the pituitary and is referred to herein as a granular of the neurohypophysis is classified according to the WHO classification of tumors of the central nervous system as a grade I.

Histologically, granular cell tumors, regardless of their location a remarkably uniform appearance. The tumor cells are arranged in nests or cell bales, large, round, polygonal, or elongated and have plenty of fine granular, eosinophilic cytoplasm, where there are sometimes large eosinophilic droplets or granules. These contain abundant hydrolytic enzymes such as acid phosphatase and can be regularly using the dye Luxol Fast Blue, staining in a proportion of cases in the PAS staining. The cell boundaries are often indistinkt, which can lead to the impression of a syncytial cell association. The nuclei are small, centrally located and usually pyknotic hyperchromatic or, more rarely vesicular. Mitoses and slight, often degenerative atypia are rarely observed. Frequently tumor cell groups are found in the surrounding area of the small nerves. Superficially localized tumors are often accompanied by a pseudoepitheliomatösen hyperplasia of the squamous epithelium forming over dress, which must not be confused with squamous cell carcinoma.

Immunohistochemistry

Immunohistochemistry showing tumor cells of Granularzelltumors positivity for neuron-specific enolase (NSE ), CD63 (NK1 - C3 ), S- 100, and almost always for inhibin and calretinin. There is also a fine granular positivity for CD68 lysosomal antigen.

The rare malignant granular cell tumors often show a negative immunoreactivity for NSE, S -100 and vimentin.

Diagnosis and differential diagnosis

The diagnosis is made by taking a tissue sample (biopsy ) or the preparation of the completely removed tumor by the pathologist. In general, the histological picture is so characteristic that no diagnostic problems. Differential diagnosis in question, depending on the localization of schwannoma, neurofibroma, alveolar soft part sarcoma, the adult rhabdomyoma, the Histiocytoid carcinoma, leiomyoma, or gastrointestinal stromal tumor, as well as rare and reactive lesions after vorausgegangenem trauma or inflammation.

Therapy

The treatment of choice is surgical removal of the tumor. A further safety margin to the tumor is only required for the malignant variant of Granularzelltumors.

Forecast

As usually benign neoplasm with a slow growth of the granular cell shows a good prognosis. The recurrence rate after surgical therapy is less than 5 percent; a recurrence of the tumor is generally due to an incomplete removal. Malignant degeneration is observed in no more than 2-3 percent of cases. It comes in the course of frequent metastasis with ultimately fatal.