Mucosal melanoma is a variant of melanoma that accounts for 0.8-1.8% of all melanomas and portends a poor prognosis. We present a case of palatal mucosal melanoma initially diagnosed as poorly differentiated squamous cell carcinoma of the palate treated with maxillectomy and immediate free fibula reconstruction.
Report of a Case
A 55 yo male with a history significant for daily alcohol, tobacco (40 pack-year), marijuana use, as well as chronic sun exposure was referred to our clinic with a biopsy confirmed diagnosis of poorly differentiated squamous cell carcinoma of the palate. Due to the pigmented appearance and low likelihood of primary invasive squamous cell of the palate, a second biopsy was performed on a second palatal lesion and the photomicrographs from the initial biopsy were reviewed. The review yielded a revised diagnosis of mucosal superficial spreading melanoma. A skin survey did not reveal lesions suspicious for cutaneous melanoma. A PET scan revealed significant uptake isolated to the hard palate.
Neck and chest CT with contrast scans did not demonstrate evidence of metastasis or nodal involvement. No bony erosion of the bone or evidence of lymph node involvement was visible on imaging. Multiple sub-centimeter scattered nodules were noted throughout bilateral lung fields consistent with a history of chronic smoking.
The tumor was staged as a cT3N0MO mucosal melanoma. The patient was presented at the University of Texas / Hermann Memorial Texas Medical Center head and neck multidisciplinary tumor board and the consensus was made to proceed with surgery followed by adjunctive radiotherapy. Surgical intervention was planned for bilateral subtotal maxillectomy, elective neck dissections and immediate free fibula flap reconstruction using Virtual Surgical Planning Reconstruction through 3D Systems Medical Modeling.
The patient tolerated the procedure well; the flap remained well perfused with a robust doppler signal. The nearest margin was 1.5 cm. Final pathology demonstrated the lesion to be a mucosal melanoma, clear cell type with depth of invasion of 0.8cm and 1.5cm in greatest dimension. No boney or lymphovascular invasion was noted. All margins were free of tumor. The tumor was staged according to the AJCC staging system and was given the status of stage III. All lymph nodes dissected were free of tumor cells. S-100 and HMB-45 mixed Immunohistochemical staining method was used in this specimen to detect the lesion.
Primary SSCa of the hard palate is exceedingly rare. More often, squamous cell carcinoma involving the palate results from invasion of an alveolar mucosal tumor onto the palate. A high index of suspicion should alert the clinician to review the photomicrograph when presented with a diagnosis of squamous cell carcinoma of the hard palate. In this case, the addition of irregular, ill-defined pigmented lesions in the vicinity of the biopsied lesion may further increase the index of suspicion and widen the differential to include melanoma.
Mucosal melanoma remains a challenging disease to treat with an unpredictable recurrence. Future treatments based on genetic variations within the tumor and host holds promise in novel therapeutic development. Surgical intervention for localized disease affords the best chance for recovery. In theory, immediate reconstruction with a free flap has the potential to delay diagnosis of disease recurrence but this concept has not been supported in the literature. Further, current imaging techniques allow for the evaluation and detection of occult disease deep to a reconstruction.