skin granular cell tumor

What are Granular Cell Tumors?

Granular cell tumors (GCTs) are rare, generally benign soft tissue neoplasms that originate from Schwann cells. They can occur in various parts of the body, including the skin, tongue, breast, gastrointestinal tract, and respiratory tract.

Characteristics of Skin Granular Cell Tumors

• Location: GCTs usually develop on any skin or mucosal surface, but are most commonly found on the tongue (40% of cases).
• Appearance: They can appear as firm, fixed masses with overlying skin changes.
• Size: The tumors are typically small, less than 2 cm in size.
• Histopathology: Microscopically, GCTs show broad fascicles of tumor cells arranged in nests or sheets infiltrating the dermis and dermal structures. The tumor cells are large in size, with small, uniform granules.

Subtypes

There are two known subtypes of GCTs: benign (more common) and malignant. Malignant GCTs behave similarly to malignant peripheral nerve sheath tumors and have a 50% rate of metastasis.

Demographics

• Age: GCTs can occur at any age, but are more commonly found in adults.
• Sex: Females are affected more often than males.

References

• [1] Aoyama K, Kamio T, Hirano A, et al. Granular cell tumors: a report of six cases. World J Surg Oncol. 2012;10:1–6. doi: 10.1186/1477 ...
• [3] Rekhi B, Jambhekar NA. Morphologic spectrum, immunohistochemical analysis, and clinical features of a series of granular cell tumors of soft tissues: a study from a tertiary referral center.
• [13] WHO Classification of Tumours Editorial Board. Soft tissue and bone tumours [Internet]. Lyon (France): International Agency for Research on Cancer; 2020 [cited 2024 ...

Common Signs and Symptoms of Skin Granular Cell Tumor

Skin granular cell tumors are typically characterized by the presence of one or more nodules under the skin, which can be painless and slow-growing. Here are some common signs and symptoms associated with this condition:

• Painless nodules: The most common symptom is the presence of a single or multiple painless nodules under the skin.
• Skin-colored or brown-red lumps: These nodules are usually skin-colored or brown-red in color, and can be smaller than 3-4 cm in diameter.
• Solitary or multiple tumors: While most granular cell tumors occur as solitary lesions, up to 10% of cases may present with multiple tumors on the body.
• Non-painful and slow-growing: These nodules are typically non-painful and grow slowly over time.

Additional Symptoms

In some cases, granular cell tumors can cause additional symptoms depending on their location. For example:

• Oral cavity lesions: When these tumors occur in the oral cavity, they may manifest as painless, slow-growing nodules on the tongue or other mucosal surfaces.
• Other symptoms: Rarely, granular cell tumors can cause soreness, discomfort, or difficulty chewing.

Important Notes

It's essential to note that while most granular cell tumors are benign (non-cancerous), some may be locally aggressive. If you suspect a skin granular cell tumor, it's crucial to consult with a medical professional for proper diagnosis and treatment.

References:

• [12] Skin-colored or brown-red lumps under the skin, typically in the head and neck
• [13] Granular cell tumors often present as skin-colored or brown-red, solitary, painless, and slow-growing nodules smaller than three to four centimeters in diameter in the head and neck area.
• [14] Granular cell tumours may present with a variety of symptoms, largely dependent on their location. In the oral cavity, these tumours may manifest as painless, slow-growing nodules on the tongue or other mucosal surfaces.

Diagnostic Tests for Skin Granular Cell Tumor

Skin granular cell tumors can be diagnosed through a combination of clinical examination, imaging studies, and histopathological evaluation.

• Clinical Examination: During a clinical examination, healthcare providers look for characteristic nodules and assess symptoms. This is often the first step in diagnosing skin granular cell tumor.
• Imaging Studies: Imaging studies such as ultrasound or MRI may be used to confirm the presence of a tumor and rule out other conditions.
• Histopathological Evaluation: A biopsy, which involves removing a sample of tissue from the tumor, is usually necessary for an accurate diagnosis. The biopsy sample is then examined under a microscope by a pathologist.

Diagnostic Criteria

The diagnosis of granular cell tumor is based on histopathologic findings and ultrastructural and immunohistochemistry studies [5]. The presence of granular cells that stain positivity for S-100 protein is a key diagnostic feature [8, 9].

• Immunostain for S-100: Immunostaining for S-100 protein can help confirm the diagnosis of granular cell tumor.
• Electron Microscopy: Electron microscopy may be used to substantiate the diagnosis of granular cell tumor.

Other Diagnostic Tests

While not always necessary, other diagnostic tests such as fine needle aspiration cytology (FNAC) or excision biopsy may be performed in some cases [7].

• Fine Needle Aspiration Cytology (FNAC): FNAC can be used to obtain a sample of cells from the tumor for examination.
• Excision Biopsy: An excision biopsy, which involves removing the entire tumor, is often preferred over punch or shave biopsy.

References

[5] Fahim S. Granular cell tumors: A review of the literature. [2022]

[7] Is fine needle aspiration cytology a useful diagnostic tool for granular cell tumors? A cytohistological review with emphasis on pitfalls.

[8] Bitar M. Investigations showed on skin biopsy, microscopic proliferation of benign granular cells, which stained positivity for S-100 protein. These traits were [2011]

[9] Igbokwe MM. GCTs are characterized by the presence of granular cells that stain positivity for S-100 protein [2022]

Treatment Options for Granular Cell Tumors

Granular cell tumors (GCTs) are rare, benign or malignant neoplasms that can occur in various parts of the body, including the skin. While surgical excision is often the primary treatment option, there are other drug treatments being explored and used in certain cases.

Surgical Excision

The most common treatment for granular cell tumors is local surgical excision, which involves removing the tumor along with a margin of surrounding tissue to ensure complete removal (5). This approach is usually effective for benign GCTs, but may not be sufficient for malignant ones, which can recur and metastasize.

Targeted Therapies

Recent studies have investigated targeted therapies as potential treatment options for granular cell tumors. One such therapy is pazopanib, a tyrosine kinase inhibitor that has been shown to stabilize disease progression in metastatic malignant GCT (6). Another combination of pazopanib and crizotinib was reported to achieve disease control for four months in one patient (8).

Cryoablation

A novel method for treating granular cell tumors using cryoablation, a technique that exposes tumor tissue to extreme cold temperatures, has been described (7). This approach may offer an alternative treatment option for patients who are not candidates for surgery.

Other Treatment Options

While the above-mentioned treatments have shown promise, it's essential to note that granular cell tumors are rare and can be challenging to treat. Other treatment options, such as chemotherapy or radiation therapy, may also be considered on a case-by-case basis (12).

In summary, while surgical excision remains the primary treatment option for granular cell tumors, targeted therapies like pazopanib and cryoablation offer potential alternatives for patients with malignant or recurrent GCTs.

References:

• [5]
• [6]
• [7]
• [8]
• [12]

The differential diagnosis for granular cell tumors (GCTs) in the skin can be extensive and varied, depending on the location and characteristics of the tumor.

Common Differential Diagnoses

• Melanocytic neoplasms [2]
• Scirrhous breast carcinoma [3]
• Chronic inflammation showing granular histiocytes [4]
• Rhabdomyoma [12]
• Hibernoma, ASPS, and other subcutaneous tumors [4]

Other Possible Differential Diagnoses

• Metastatic renal cell carcinoma and apocrine carcinoma of the breast [5]
• Malignant fibrous histiocytoma, malignant peripheral nerve sheath tumor, and other soft tissue sarcomas [6, 11]
• Granular cell leiomyoma [9]
• Alveolar soft parts sarcoma, adnexal tumors, apocrine carcinoma, basal cell carcinoma, cholangiocarcinoma, colonic adenoma, cystic lesions, dermatofibroma, dermoid cyst, desmoid tumor, duct ectasia, fat necrosis, and other skin and subcutaneous lesions [10]

Key Points to Consider

• The clinical presentation of GCTs can be variable, ranging from a papule to a round or oval nodule, which can make diagnosis challenging.
• The differential diagnosis for GCTs includes both benign and malignant lesions with abundant eosinophilic granular cytoplasm [14].
• Treatment and management of GCTs remain an issue of discussion due to the controversy surrounding the distinction between benign, atypical, and malignant GCTs [15].

It's essential to consider these differential diagnoses when evaluating skin granular cell tumors, as accurate diagnosis is crucial for determining the appropriate treatment plan.