Dermal Melanoma in a Transplant Patient

A 37-year-old white woman on over 10 years of immunosuppressive therapy for two successive renal transplants was seen in our dermatology clinic for a tender lesion on her left eyebrow which had grown rapidly over the previous few months. Physical exam revealed a 4 mm, pink, tender papule with a 9 mm subcutaneous component (Figure 1a). There was no lymphadenopathy.

Excisional biopsy showed a dermal nodular malignant neoplasm with spindled and epithelioid malignant cells with frequent mitoses without an epidermal connection (Figure 1 b and c). Immunohistochemical staining confirmed the diagnosis of malignant melanoma, with a Breslow depth of at least 6 mm and Clark level of at least IV. Subsequent complete skin exam revealed no cutaneous primary lesion. A PET scan was negative for metastatic disease.

The case was discussed at our institution's cutaneous oncology tumor board by a multidisciplinary team including transplant nephrology, dermatologic surgery, dermatopathology, surgical oncology and plastic surgery. The consensus diagnosis was primary dermal melanoma. Given the cosmetically sensitive area in a young woman, excision with 1 cm margins was recommended along with sentinel lymph node biopsy (SLNB).

The excision showed no residual tumor, and the SLNB was negative. Skin graft repair was performed to allow close monitoring for recurrence. With a classic melanoma of this depth, recommendations might be to stop immunosuppression and sacrifice the transplanted kidney for a potentially increased chance of survival, though this is controversial. In this case the multidisciplinary decision was to decrease, but not stop, immunosuppression. Mycophenolate mofetil was discontinued, but the patient's other immunosuppressants were maintained. There is no evidence of disease at 17 months.

The diagnosis of primary dermal melanoma was made in this case based on the solitary focus of dermal disease, lack of epidermal connection and the absence of a primary epidermal lesion. Primary dermal melanoma has been reported as a subtype of melanoma¹ that may have a better prognosis than classic melanomas of equal thickness.^1,2,3,4,5 The true origin of primary dermal melanoma is unknown.¹ Bowen et al. hypothesized that these tumors may originate from non-epidermal melanocytes, embryological remnants, or deeper appendageal- associated melanocytes.³ Published data show that these tumors do not behave like stage IV metastatic disease in skin from an unknown primary site, but instead correspond to fiveyear survival rates ranging from 80 percent to 100 percent in some case series.^1-5

Some melanomas may be quite sensitive to immune system control. In reports, advanced melanoma has regressed upon withdrawal of immunosuppression.^6,7 Likewise, quiescent metastatic melanoma has been unwittingly transplanted, leading to the death of the immunosuppressed organ recipient.⁸ In this case, immunosuppression was decreased but not withdrawn.

This case of a thick dermal melanoma in a renal transplant patient raised complex issues regarding prognosis and management. A multidisciplinary team was necessary to weigh competing risks and benefits. The patient remains under close monitoring with a still uncertain long-term prognosis.

The authors would like to thank Dr. George F. Murphy, who provided an expert opinion in this case.

The authors have no relevant conflicts of interest to disclose.