Introduction:
Granular cell tumors are uncommon neoplasms originating from Schwann cells with distinct pathologic features. They can be benign or malignant, usually seen in the skin, mouth, and gastrointestinal systems. They must be adequately treated to avoid the recurrence or spread of malignant tumors. Abrikossoff, a Russian pathologist, reported granular cell tumors in 1926. Granular cell myoblastomas were given their names since they were thought to be of muscle origin. However, they are currently considered Schwannian because of immunohistochemical stains and electron microscopy. A subpopulation of S100-negative ‘non-neural’ granular cell tumors has been found.
What Is a Granular Cell Tumor?
A granular cell tumor arises from Schwan cells, which are benign, rare, and soft tissue tumors. It was considered a form of myoblastoma, but recent studies have shown that it is more neural in origin. Some genetic mutations are known to cause granular cell tumors, but the exact cause is not known.
What Is the Occurrence of Granular Cell Tumors?
The most commonly reported sites are the epidermis, digestive system, oral cavity, and subcutaneous tissue. They can, however, arise in any body part, including the breast, neurological system, bladder, genitourinary tract, and lungs. Women in their fourth to sixth decades of life are more likely to be harmed than males.
Granular cell tumors often present as solitary, painless nodules smaller than three to four centimeters and can be discovered by chance. The great majority of people are sluggish. However, one to two percent of these lesions might be malignant based on histologic criteria or the presence of metastases, with a poor prognosis and limited curative options beyond surgical removal.
What Is the Epidemiology of Granular Cell Tumors?
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Granular cell tumors can occur at any age, although they are more frequent in the fourth to sixth decades.
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These tumors are more commonly found in women.
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African-American people account for two-thirds of all benign lesions.
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More than 70 % of people with malignant cutaneous tumors are Caucasian.
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These are uncommon tumors. Although most are solitary, 7–29% of individuals might present with numerous lesions, 30 % of which include the skin and subcutaneous tissue.
What Is the Etiology of Granular Cell Tumors?
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The genesis of granular cell tumors is poorly defined, and their genetic origins and pathophysiology remain unknown.
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Although it is recognized that these cancers may exhibit recurrent genetic alterations in the context of specific disorders, the mutations causing sporadic carcinogenesis were just recently discovered using whole-genome sequencing.
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Multiple granular cell tumors are known to be related to:
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LEOPARD syndrome.
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The authors discovered PTPN11 gene alterations in granular cell cancers linked to leopard and Noonan syndromes.
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It has also been suggested that because this mutation is present in all three disorders, the etiology of multiple granular cell cancers may be connected to aberrant RAS or MAPK pathway cell signaling.
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Granular cell tumors are linked to germline PTEN mutations in patients with PTEN hamartoma tumor syndrome.
What Are the Signs and Symptoms of Granular Cell Tumors?
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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.
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They are rarely unpleasant or itchy.
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The most commonly affected are the skin, oral cavity, respiratory tract, gastrointestinal tract, and breast.
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Their high frequency in the tongue and skin corresponds to the high concentration of peripheral nerves in those locations.
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They have been found in every organ system, including the thyroid, the genitourinary tract, the neurohypophysis, and the pancreaticobiliary system.
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They may appear as numerous nodules as well.
Gastrointestinal Tract (GIT) -
These tumors are frequently discovered incidentally during screening in the gastrointestinal tract, and patients are typically asymptomatic. The distal esophagus is the most commonly affected, followed by the anus, duodenum, and stomach, while occurrences in the colon, biliary tract, and rectum have also been found.
Breast -
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Granular cell tumors can develop anywhere in the breast, including all four quadrants, the axilla, and the nipple, the upper inner quadrant of the supraclavicular nerve distribution.
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70 % manifest as palpable masses, whereas the remainder is discovered inadvertently or during screening without a palpable mass on the test.
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Most are asymptomatic, although some patients have experienced discomfort, pruritis, skin thickness, retraction, dimpling, and reactive lymphadenopathy at the presentation time.
Mouth -
In the oral cavity, they are most commonly visible on the front tongue as a complex yellow or pink, non-painful, single nodule. Although they can be detected on the lip, palate, and buccal mucosa, they account for fewer than 20 % of all oral cavity granular cell tumors.
How Are Granular Cell Tumors Diagnosed?
Radiology Imaging -
It is often not pursued before the excisional biopsy for small, benign-appearing nodules in the skin or oral cavity. On the other hand, tumors in the breast, gastrointestinal system, extremities, soft tissue, and other unusual places are often scanned because they cannot be recognized clinically from other benign or malignant lesions.
What Is the Treatment of Granular Cell Tumors?
Surgery-
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For granular cell tumors in practically all locales, whether benign or malignant, complete excision to negative margins with diligent clinical follow-up is indicated.
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Smaller skin lesions are diagnosed with wide local excision, while more extensive lesions may require a biopsy followed by excision.
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Given the propensity of these cancers to return with positive margins, Mohs surgery is sometimes used to assure total tumor excision, especially in aesthetically and functionally important regions.
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A sentinel lymph node biopsy is only indicated for clinically or histologically suspected malignant lesions.
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Although some treatments recommend lymph node dissection for palpable lymph nodes or biopsy-proven metastatic illnesses, others do not.
Radiation Therapy and Chemotherapy
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Chemotherapy and radiation treatment are now thought to have limited function.
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Modalities have been successfully utilized on individuals with malignant tumors and metastatic illnesses.
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The sarcoma medication Pazopanib can treat some recurring malignant granular cell tumors. However, no current standard chemotherapy regimen for malignant or metastatic illness exists.
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Adjuvant radiation treatment has been contentious and ill-defined for recurring malignant tumors or inoperable metastases.
Conclusion:
The prognosis of granular cell tumors is influenced by whether the lesions are malignant or benign. Benign tumors respond well to extensive local excision and seldom return or spread. On the other hand, patients with significant malignant tumors and metastatic disease have terrible results. Therefore, contacting diagnostic specialists and meeting with an interdisciplinary group of sub-specialists is critical.
