|LETTER TO THE EDITOR
|Year : 2015 | Volume
| Issue : 3 | Page : 446-447
Metastatic malignant melanoma in a young adult with unknown primary
AS Shenoy1, HM Desai1, VS Kavishwar1, HV Savant2
1 Department of Pathology, TN Medical College and BYL Nair Charitable Hospital, Mumbai, Maharashtra, India
2 Department of Neurosurgery, TN Medical College and BYL Nair Charitable Hospital, Mumbai, Maharashtra, India
|Date of Web Publication||18-Feb-2016|
H M Desai
Department of Pathology, TN Medical College and BYL Nair Charitable Hospital, Mumbai, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Shenoy A S, Desai H M, Kavishwar V S, Savant H V. Metastatic malignant melanoma in a young adult with unknown primary. Indian J Cancer 2015;52:446-7
Melanoma metastasis to the bone and bone marrow is exceedingly rare. We report here a case of metastatic melanoma to the skull bone at presentation in a young adult.
A 23-year-old male presented with history of bone pains and fever since 8 months. X-ray skull and computed tomography (CT) brain were suggestive of multiple expansile lytic lesions limited to the frontal skull bones [Figure 1]. The age and multiple skull bone lytic lesions prompted the clinical suspicion of a histiocytic disorder versus a plasmacytoma.
|Figure 1: CT scan images showing multiple osteolytic lesions in the skull bones|
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Frozen section examination of the bony lesion showed a tumor composed of large pleomorphic cells arranged in sheets. The paraffin sections showed a tumor composed of cells with clear cytoplasm, vesicular nucleus, and prominent eosinophilic nucleolus with no identifiable pigment arranged in sheets, clusters and nests [Figure 2]. Few mitotic figures were seen and necrosis was focal. On immunohistochemistry (IHC), the tumor cells diffusely expressed vimentin, HMB-45, S-100, focally Melan-A and were negative for cytokeratin (CK), epithelial membrane antigen (EMA), CD-34 and CD-56 leading to a diagnosis of metastatic deposits of amelanotic melanoma [Figure 3].
|Figure 2: Microscopic section showing tumor cells arranged in sheets and nests with a clear to eosinophilic cytoplasm (H and E, ×100). Inset: Tumor cells showing prominent eosinophilic nucleolus (marked with arrows) (H and E, ×400)|
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|Figure 3: Tumor cells showing positivity for vimentin, HMB-45, S-100 and Melan-A immunohistochemical (IHC) stains|
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A thorough clinical and laboratory investigation identified no primary lesion. On repeated questioning, the patient faintly remembered having excised a cervical skin lesion 4 years back reported as a Spitz nevus, which could have been the possible misdiagnosed primary melanoma lesion.
Such kind of presentation has very limited treatment options. Radical resection of bone with radiotherapy with or without chemotherapy has been beneficial in certain cases of solitary skeletal metastasis. Immunotherapy with interleukins-2 (IL-2) or interferons (IFN) has been beneficial in appropriately selected cases. In view of multiple lesions, the patient was referred to an oncocenter for further management by chemotherapy and immunotherapy.
The problems we encountered were that the patient was young, giving no prior operative history, radiological features suggesting plasmacytoma versus histiocytic neoplasm and tissue sections favoring a malignant epithelioid neoplasm. Only a wide panel of immunohistochemical stains helped us reach a definitive diagnosis. Very few cases have been reported in children and though majority of the cases occur after puberty, melanomas remain distinctly uncommon in early adulthood.
Melanoma is a highly aggressive tumor with a great propensity for metastasis. The metastatic sites include local lymph nodes, brain and rarely bone. Of the 11 cases of disseminated osseous metastasis reported by Huang et al., skull involvement was seen in three cases. However, Metastatic melanoma of unknown primary origin accounts for upto 8% of all melanoma cases in literature, the possible mechanism being complete dissolution or regression of the primary by the time the metastasis occurred.
Since our case had a history of excision of a cervical skin lesion 4 years back, we presume that this could be the possible primary melanoma lesion, misdiagnosed as a Spitz nevus.
In selected Stage IV melanoma patients, aggressive surgical approach has been reported since non-surgical treatment of Stage IV melanoma has been beneficial in only few selected cases. The 5 year survival rate after bony metastasis is 5%.
To conclude, the possibility of metastatic melanoma should be considered in the differential diagnosis of any lytic bony lesion in the skull bones even in a young adult and even without identifiable primary at presentation. Furthermore, lesion in a young adult with resemblance to Spitz nevus needs careful evaluation for the possibility of malignant melanoma.
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[Figure 1], [Figure 2], [Figure 3]