Granular cell tumor of the chest wall: the first case report and literature review

Introduction

Background

Granular cell tumor (GCT), also referred to as granular cell nerve sheath tumor or granular cell myoblastoma, is an exceedingly rare lesion primarily characterized by benign hyperplasia (1). The origin and nature of GCT have been debated, but they are generally thought to arise from Schwann cells, supported by pathological, electron microscopy, and immunohistochemical evidence (2,3). GCT constitutes 0.5% of all soft tissue tumors, with a slightly higher incidence in women than men (male-to-female ratio approximately 1:1.3–2). The average age of onset is 41–43 years, though malignant cases predominantly occur in older patients (67–69 years) (4,5).

Rationale and knowledge gap

GCT was first described by Professor Abrikossoff in 1926 in the tongue, and has since been identified in various anatomical locations (1,4-6). It predominantly occurs in the oral cavity and tongue, followed by the skin and subcutaneous tissue, but may also affect the stomach, esophagus, larynx, bronchus, mammary gland, pituitary gland, and skeletal muscle (7). GCT of the chest wall is particularly uncommon, with limited documentation in international literature (8,9).

Objective

This case report aims to fill this knowledge gap by providing a detailed description of the clinical characteristics, imaging findings, pathological features, and treatment of GCT of the chest wall. We present this case in accordance with the CARE reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-124/rc).

Case presentation

The patient, a 32-year-old female, presented with a mass on the right anterior chest wall for over 4 years. Initially discovered as a painless swelling with the size of a soybean, it had no associated symptoms and was monitored regularly. A year ago, a chest computed tomography (CT) scan revealed a soft tissue density shadow near the right side of the sternal handle, measuring approximately 2.5 cm × 2.5 cm × 1.5 cm with 30 Hounsfield units (HU). No treatment was administered at that time. Two weeks ago (2021-08-26), a follow-up CT scan showed that the mass had the same dimensions but with increased density of 52 HU, indicating less uniform density (Figure 1). The patient now (2021-09-08) experienced anterior chest discomfort without fever or weight loss and sought surgical intervention. Family history was significant for paternal leukemia.

Figure 1 Computed tomography scan demonstrating a mass, near the right side of the sternal handle.

Physical examination revealed no palpable enlargement of superficial lymph nodes, and no specific examination of the heart, lungs, or abdomen was conducted. Specialist examination identified a local bulge at the third thoracic costal joint on the right side of the sternal stem. The skin appeared normal, with no pigmentation, redness, swelling, or elevated temperature. The mass was hard, non-tender, poorly defined from surrounding tissues, and exhibited limited mobility. There was no tenderness, discharge, or pus in the breast. Routine blood, urine, and stool tests, as well as liver and kidney function tests and tumor markers, were normal. The chest wall mass was excised under general anesthesia. A fusiform skin incision revealed the mass located in the third intercostal dermis anterior to the sternum, partially enveloped by muscle, and lacking a distinct capsule. The tumor was completely excised with an electric knife and submitted for pathological analysis (Figure 2A). Postoperative pathological examination report: Macroscopic examination reveals fusiform skin and subcutaneous tissue measuring 4 cm × 3 cm × 2.5 cm, with gray nodules of 3.5 cm × 3 cm × 1.5 cm beneath the skin, located 1 cm from the fusiform skin. The section appears gray and tough (Figure 2B). Microscopically, subcutaneous fibroplasia with hyaline degeneration is observed, along with nested tumor tissue comprising oval cells with abundant cytoplasm and a granular appearance (Figure 3). Immunohistochemical analysis shows CK (−), Desmin (−), S-100 (+), β-catenin (membrane +), CD34 (vessel +), STAT6 (−), p16 (+), Ki-67 (2%+), Sox-10 (+), TFEB (weak +), HMB45 (−), MelanA (−), INI1 (+), Calretinin (+), inhibin-α (−), TFE3 (+), CD68 (+). The findings suggest a granulosa cell tumor with poorly defined, invasive growth at the periphery, measuring 3.5 cm × 3 cm × 1.5 cm. Routine anti-inflammatory treatment and wound compression bandaging were administered, with discharge occurring one week later (Figure 4). No recurrence or metastasis has been observed 3 years post-operation, and follow-up continues.

Figure 2 Surgical specimens. (A) Complete resection of the tumor; (B) the tumor section appears gray and tough.

Figure 3 Hematoxylin and eosin staining. (A) Granular cell tumor of the chest wall under the microscope (×0.5); (B) granular cell tumor of the chest wall under the microscope (×80).

Figure 4 Postoperative wounds.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and the accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

Clinical characteristics

Clinically, GCT of the skin lesions typically presents as light red to yellow firm nodules, often solitary, measuring 3.0–5.0 cm in diameter, with indistinct boundaries. These nodules can rupture, may be multiple, and can involve various tissues and organs (10,11). Most cases are characterized by painless solitary nodules, though some may exhibit tenderness, intermittent dull pain, or pruritus, with disease progression ranging from days to years. Notably, malignant granular cells are usually larger (mean diameter >5 cm) and frequently associated with local infiltration or metastasis (12,13).

Imaging findings

CT/magnetic resonance imaging (MRI) characteristics of subcutaneous soft tissue tumors typically include round nodules with soft tissue density on CT scans. On T1-weighted imaging (T1WI), these tumors exhibit slightly lower, equal, or slightly higher signals compared to adjacent muscles, while T2-weighted imaging (T2WI) shows slightly higher signals. Tumors are generally less than 3.0 cm in diameter, with no calcification, cystic degeneration, necrosis, or bleeding. They have well-defined edges and exhibit mild, uniform enhancement upon contrast administration, similar to adjacent muscle tissue (11). In contrast, malignant granulocyte tumors are characterized by diameters usually exceeding 4.0 cm, indistinct boundaries with adjacent soft tissues, heterogeneous density or signal within the mass, increased enhancement, and associated lymphadenopathy.

Pathological features and differentiation between benign and malignant GCT

Histological analysis: macroscopically, tumors appeared predominantly pale yellow or grayish-white with a medium texture. Microscopically: (I) tumor cells are large and polygonal with pale-stained cytoplasm filled with small eosinophilic granules, showing positive staining for PAS and S-100 protein; (II) these cells typically have a single, centrally located, round or oval nucleus with dark chromatin, and lack mitosis, hemorrhage, or necrosis; (III) the overlying epidermis often exhibits marked pseudoepithelioid hyperplasia (12). Benign GCT are characterized by round or polygonal cells with eosinophilic granular cytoplasm, a small central nucleus, fine chromatin, and eosinophilic bodies with a clear halo in the cytoplasm. GCT are generally benign, with malignancy occurring in 1% to 3% of cases (13). Factors indicating malignant transformation include rapid growth, diameter >4 cm, cell necrosis, fusiform cells, enlarged vacuolar nuclei with prominent nucleoli, pleomorphic cells, active mitosis [>2/10 high power field (HPF)], high nuclear-to-cytoplasmic ratio, and local recurrence (14). An immunohistochemical p53 positive rate >50% and a Ki-67 index >10% may also suggest malignancy (15,16). Some cases are associated with pseudoepithelioma or interstitial fibrosis, potentially leading to misdiagnosis as squamous cell carcinoma or fibroma. Immunohistochemically, GCT is positive for S-100 and vimentin, but negative for CK, desmin, and actin (17). Clinically, differentiation from dermatofibroma, leiomyoma, breast fibroadenoma, and breast cancer is necessary.

Pathological diagnosis remains the gold standard. The Fanburg-Smith criteria are predominantly employed to evaluate biological behavior based on histological features and prognostic factors, such as tumor size exceeding 5.5 cm, local recurrence, and metastasis (18). According to the FS criteria, a diagnosis of malignant GCT requires at least three histological indicators of malignancy, such as necrosis, nuclear pleomorphism, and nuclear separatism (19). Additionally, a CD34 “wrapped” positive pattern around tumor cell nests may aid in differential diagnosis. The immunohistochemical profile of GCT strongly supports its origin from the nerve sheath, with S-100 protein showing 100% positivity, CD68 ranging from 83.8% to 100% positivity, and high positivity for neuron-specific enolase, while smooth muscle markers are negative. CD56 and synaptophysin exhibit positive rates of 100% and 82.6%, respectively, indicating a propensity for neuroendocrine differentiation. Notably, the Ki-67 proliferation index is typically below 10% but may increase in malignant cases (20).

Treatment and prognosis

Complete surgical resection is the preferred treatment for GCT, as radiation therapy proves ineffective. Patients tend to cooperate better with surgeons under general anesthesia, facilitating a smoother surgical procedure and enhancing patient experience. Conversely, local anesthesia may lead to inadequate anesthetic effects, negatively impacting patient experience during surgery. Intradermal corticosteroid injections may offer temporary improvement. The prognosis for benign granulocytoma post-resection is favorable, with a low recurrence rate. In contrast, malignant granulocytoma has a poor prognosis, with a 5-year survival rate of 60% and a 10-year survival rate of 30% (21). Post-surgical recurrence and metastasis are common, with rates of 50% and 60% at 5 years, respectively (22,23). Postoperative follow-up is essential. For larger granulosa cell tumors, extended resection may be required due to the risk of malignancy or recurrence (24). Malignant GCTs necessitates extensive local resection, as they are prone to lymphatic metastasis, warranting regional lymph node dissection if needed (25). Multiple GCTs (5% to 10%) require vigilance for potential malignancy, with long-term imaging monitoring advised (26).

Strengths and limitations

This study provides the report of GCT of the chest wall, offering new insights into the clinical characteristics, imaging findings, pathological features, and treatment of this rare tumor. The detailed case description, combined with imaging and pathological data, along with long-term postoperative follow-up data, enhances our understanding of GCT of the chest wall.

However, there are some limitations in this case report. First, due to the rarity of the condition, this study is based on a single case and lacks a sufficient sample size for statistical analysis, making it difficult to comprehensively generalize the characteristics and behavior of GCT of the chest wall. Second, although the follow-up period has reached 3 years, it is still insufficient to evaluate the very long-term risks of recurrence and metastasis. Long-term monitoring is still required to improve the prognostic data. Finally, the study does not delve into the molecular mechanisms of GCT. Future research could consider conducting genetic testing and molecular biological studies to further reveal the pathogenesis of GCT.

Comparison with similar research

Compared with previous reports of GCT in other anatomical locations, this case shares some common features, such as the benign nature of the tumor and the effectiveness of surgical resection. However, the location of the tumor in the chest wall is unique, and this report provides new information on the clinical management of this specific site.

Explanations of findings

The tumor’s location in the chest wall may have contributed to its delayed diagnosis. The lack of specific symptoms and the rarity of this tumor type may have also played a role. The favorable prognosis after surgical resection is consistent with the typical behavior of benign GCT.

Implications and actions needed

This case highlights the importance of considering GCT in the differential diagnosis of chest wall tumors. It also underscores the need for complete surgical resection and postoperative follow-up to monitor for recurrence or metastasis.

Conclusions

This report presents the rare case of GCT of the chest wall. Complete surgical resection is the preferred treatment, and the prognosis is favorable. Clinical follow-up was performed via phone or email. The patient reported a good general condition, no discomfort at the surgical site, and no tumor recurrence. This case contributes to the understanding of GCT of the chest wall and provides guidance for future clinical practice.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-124/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-2025-124/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-2025-124/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration and its subsequent amendments. Written informed consent was obtained from the patient for the publication of this case report and the accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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