Amelanotic melanoma masquerading as a granular cell lesion

Area of Science:

• Oncology
• Dermatopathology
• Oral Pathology

Background:

• Amelanotic melanoma (AM) poses diagnostic difficulties due to non-specific clinical and histological features.
• Oral mucosal AM is particularly uncommon, further complicating its identification.
• Immunohistochemistry is essential for diagnosing amelanotic lesions.

Purpose of the Study:

• To report a rare case of amelanotic melanoma of the oral mucosa.
• To highlight the diagnostic utility of immunohistochemistry in challenging AM cases.
• To describe a unique histological presentation of AM mimicking a granular cell lesion.

Main Methods:

• Case report of a 50-year-old male with mandibular gingival growth.
• Histopathological examination of the tumor.
• Sequential immunohistochemical staining using markers including vimentin, S100, HMB45, and Melan-A.

Main Results:

• The oral tumor exhibited a histological appearance resembling a granular cell lesion, a presentation not previously documented in AM.
• Immunohistochemical analysis confirmed the diagnosis of amelanotic melanoma.
• Positive staining for vimentin, S100, HMB45, and Melan-A was crucial for diagnosis.

Conclusions:

• This case underscores the importance of immunohistochemistry in diagnosing amelanotic melanoma, especially with unusual histological mimics.
• Amelanotic melanoma can present with diverse histological patterns, requiring a comprehensive diagnostic approach.
• Early diagnosis and appropriate treatment, including surgical excision and radiotherapy, are vital for managing oral AM.