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Malignant melanoma presenting as a mediastinal mass
C L Lau1, R C Bentley, J P Gockerman
1Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
The Annals of Thoracic Surgery
|April 24, 1999
Summary
This case report describes a rare instance of malignant melanoma originating in the mediastinum without a detectable primary tumor elsewhere. Diagnostic methods confirmed the presence of melanin pigment and melanoma-specific markers.
Area of Science:
- Oncology
- Pathology
Background:
- Malignant melanoma typically arises from the skin, but can present in extrathoracic sites or as an unknown primary.
- Mediastinal masses can have diverse origins, requiring thorough diagnostic evaluation.
Observation:
- A patient presented with a mediastinal mass that, upon microscopic examination, showed features consistent with malignant melanoma.
- Focal melanin pigment was observed within large epithelioid cells.
Findings:
- Fontana stain confirmed the presence of melanin pigment.
- Immunohistochemical analysis revealed tumor cells positive for HMB45 and S100, and negative for cytokeratin, supporting a melanoma diagnosis.
- Electron microscopy identified abundant melanosomes, definitively confirming malignant melanoma.
Implications:
- This case highlights the possibility of primary mediastinal malignant melanoma, emphasizing the importance of considering melanoma in the differential diagnosis of mediastinal tumors.
- Advanced diagnostic techniques, including immunohistochemistry and electron microscopy, are crucial for accurate diagnosis when classical features are atypical.