Investigators using a handheld dermoscopy device that allows visualization of colors, structures, and patterns in skin lesions not evident to the naked eye were able to visualize nonblanching blue and red lines in a branched pattern in two patients with in-transit cutaneous melanoma metastases.
Dr. Michael A. Marchetti and his associates at Memorial Sloan Kettering Cancer Center, New York, reported the “intriguing” visualization of dissemination for cutaneous melanoma metastases in a letter to JAMA Dermatology.
In-transit cutaneous melanoma metastases are those located more than 2 cm from the primary melanoma, but not beyond the regional nodal basin.
The first patient had wide local excision of a primary cutaneous melanoma on the forehead, and a year later, received localized irradiation for satellite skin metastases. A year after that, skin examination revealed six blue macules on the scalp more than 2 cm from the excision scar. Dermoscopy revealed nonblanching bluish lines in a branched pattern. Histopathologic examination of a skin biopsy confirmed in-transit metastatic melanoma with atypical melanocytes present in superficial dermal lymphatics, Dr. Marchetti and his associates reported (JAMA Dermatology 2015;103-5)
The second patient had a history of multiple primary melanomas, the most recent being one on the chest treated with wide local excision. At a follow-up visit 5 years later, skin examination revealed eight blue-gray macules on the chest, all more than 2 cm from the excision scar. Dermoscopy revealed nonblanching, red-bluish, fuzzy, branching lines. Histopathologic examination of a skin biopsy confirmed in-transit metastatic melanoma with atypical melanocytes present in superficial dermal blood vessels, the investigators wrote.
Typical dermoscopic features of cutaneous melanoma metastases include peripheral gray spots, atypical vessels, and a blue nevus-like pattern. The histopathologic findings in these two cases suggest that the dermoscopic color differences correspond to unique microanatomic routes of melanoma dissemination, with blue and red-blue lines corresponding to lymphatic and hematogenous dissemination of tumors, respectively, they said.
“While the factors driving lymphatic vs. hematogenous in-transit dissemination of melanoma remain unknown, as do any differences in their biologic significance, our finding is an intriguing clinical/dermoscopic/histopathologic observation,” the investigators concluded.
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