| Abstract|| |
A granular cell tumor (GCT) is a rare, usually benign soft tissue neoplasm that is commonly seen in the head and neck region. It is derived from the Schwann cells of the peripheral nerves. GCT is uncommon in children. 6-year-old girl was referred to our hospital for swelling over her left scapula, and a surgical excision was performed to remove the mass. Microscopically, the tumor was composed of cells with large granular cytoplasm and small oval to round nuclei. These cells stained positively for the following proteins: S-100, CD68, neuron-specific enolase, calretinin, and inhibin A. A GCT is usually benign, with a good prognosis, and less than 2% of the cases are reported to be malignant. It is worth noting that such tumors may arise in atypical locations and there is a possibility of malignancy.
Keywords: Child, granular cell tumor, subcutaneous nodule
|How to cite this article:|
Yilmaz ZS, Ersoz S. Granular cell tumor in a child: A rare case report. Indian J Pathol Microbiol 2020;63:478-80
| Introduction|| |
Granular cell tumors (GCTs) are rare soft tissue neoplasms originating from Schwann cells. These tumors, which are rarely diagnosed in children, exhibit a peak occurrence during the fourth through sixth decades of an individual's life, and they usually appear in women. GCTs are commonly presents as a dermal nodule without ulceration. Although a GCT usually presents as a solitary neoplasm, multiple lesions can occur infrequently. These multifocal lesions are even less common in children, and they are often associated with a family history of GCTs. GCTs can occur at any site, but they are more commonly localized in the head and neck region, and most of them arise in the oral cavity. The most common site of this neoplasm is the tongue.
Here, we have presented the case of a 6-year-old girl with a GCT over the dorsal aspect of her left scapula. An uncommon presentation site, in a young child with the typical histopathology, is discussed.
| Case History|| |
A 6-year-old girl presented to our hospital's Plastic and Reconstructive Surgery outpatient clinic with a long history of a single lesion over her left scapula. Her systemic investigation indicated no abnormalities. Upon physical examination, there was a subcutaneous nodule approximately 1 cm in size in the left scapular region. An excisional biopsy was performed based on a clinical differential diagnosis of a pseudolymphoma or neurilemmoma.
Macroscopically, no lesion was observed on the skin; however, the cross-section showed a grayish-brown nodular 1.2 cm × 0.4 cm lesion. The epidermis was normal in the histological examination, but there was a nodular lesion composed of solid nests and sheets of cells within the dermis [Figure 1]a. These cells exhibited granular cytoplasm with small oval to round nuclei [Figure 1]b. There were no mitotic figures or necrosis. The lateral surgical margins were positive. Immunohistochemically, the neoplastic cells stained positive for S-100 [Figure 2]a, neuron specific enolase (NSE) [Figure 2]b, CD68 [Figure 2]c, calretinin [Figure 2]d, and inhibin A [Figure 2]e and negative for desmin and melan-A. The Ki-67 proliferation index was less than 1%. Based on the above immunohistochemical and morphological findings, the histopathological diagnosis was a benign GCT.
|Figure 1: (a) Nodular lesion composed of solid nests within the dermis (H and E, 100×). (b) Lesion composed of a proliferation of cells with granular cytoplasm and small oval to round nuclei (H and E, 200×)|
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|Figure 2: (a) Tumor cells positive for S-100 staining (IHC 100×). (b) Tumor cells positive for neuron-specific enolase staining (IHC 100×). (c) Tumor cells positive for CD68 staining (IHC 100×). (d) Tumor cells positive for Calretinin staining (IHC 100×). (e) Tumor cells positive for Inhibin A staining (IHC 100×)|
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| Discussion|| |
GCTs, which are also called granular cell myeloblastomas or Abrikossoff' s tumors, were first described by Weber in 1854. In 1926, Abrikossoff reported that their origin was muscle tissue; however, electron microscopic examinations of the axons and positive S-100 immunohistochemical staining have indicated that they actually originate from Schwann cells.
Clinically, this neoplasm often presents as a single, solitary, asymptomatic, dermal or subcutaneous papule or nodule in adults. Multiple GCTs have rarely been reported in the literature. They may be associated with neurofibromatosis, Noonan syndrome, Watson syndrome, or growth retardation, especially in children.
Although GCTs can occur anywhere in the body, they are most commonly seen in the head and neck region (45–60% of the cases). Most of them are localized in the oral cavity, most commonly, the tongue. However, GCTs can also occur in other sites, such as the breast (15%), respiratory system (10%), and gastrointestinal system (4–6%). GCTs occur rarely in children, and in the previous studies, 40 cases under 19 years of age have been reported. The present case is rare due to its common site and age at occurrence.
A definitive diagnosis is based on the histopathological examination of a biopsy specimen. The tumor cells show granular eosinophilic cytoplasm, with centrally located vesicular or pyknotic nuclei. Large lysozymes, which stain positively with periodic acid-Schiff staining, are the reason for this granular appearance. The granular appearance of the cytoplasm and positive staining for the immunohistochemical histiocytic marker CD68 confirm the existence of histiocytes. Immunohistochemically, these tumor cells are also positive for S-100, NSE, calretinin, nerve growth factor receptor 5, and inhibin A., The neuronal origin of GCTs is supported by S-100 and NSE immunopositivity. In the literature, p53 expression and the Ki-67 proliferation index are associated with more aggressive outgrowth, and in some cases, malignant GCTs show p53 positivity and a high Ki-67 proliferation index. However, benign lesions are p53 negative, with a Ki-67 proliferation index of less than 1%. The Ki-67 proliferation index was also less than 1%, and p53 was negative in our case.
The malignant transformation of a GCT is very rare (less than 2% of the cases), and only one pediatric case of a malignant GCT has been previously reported. Fanburg-Smith et al. classified GCTs into three subtypes, benign, atypical, and malignant, and they identified six diagnostic histological criteria to categorize GCTs into these three groups. These histological criteria were as follows: necrosis, spindling, vesicular nuclei with large nucleoli, increased mitotic activity (>2 mitoses in 10 high power fields at 200× magnification), a high nuclear to cytoplasmic ratio, and pleomorphism. Three or more of these criteria are required to meet the diagnosis of malignancy, while the presence of one or two of these indicates an atypical form. If none of these criteria are featured, the diagnosis should be a benign GCT., None of the histological criteria of malignancy were seen in our case.
In GCT cases, neoplastic cells rarely extend into the epidermis, and the lesion can mimic a melanocytic neoplasm; therefore, an immunohistochemical panel should be used for the differential diagnosis. Certain benign mesenchymal tumors also have a granular appearance; however, the absence of lipid droplets excludes hibernomas and fibroxanthomas. Moreover, reactive histiocyte proliferation can also be observed in surgical trauma cases and injuries, mimicking a benign GCT. Detailed clinical information is important in the differential diagnosis of a GCT.
A wide local excision with clear margins is curative for benign GCTs, with recurrence rates of 2–8% (20% with positive margins); therefore, histological control of the surgical margins is important. In our case, no recurrence was detected during the 2-year follow-up period even though positive surgical margins were reported.
| Conclusion|| |
The present case is unique because this neoplasm was seen in a child, and it was localized to a region other than the head and neck area. It should be remembered that the tumor may arise in atypical locations. Although it is mostly benign, it may be malignant in approximately 2% of the cases. Pathologists should be aware of the pitfalls in diagnosing GCT.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to b'e reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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Zeynep Sagnak Yilmaz
Department of Pathology, Trabzon Kanuni Training and Research Hospital, 61290 Trabzon
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]