Lymph Node Melanosis in a Patient With Metastatic Melanoma of Unknown Primary

Abstract

Tumoral or nodular melanosis in the skin is considered a variation of completely regressed melanoma, presenting clinically as a suspicious pigmented papule or nodule. Microscopically, the lesion consists of a nodular accumulation of heavily pigmented melanophages in the dermis, staining positive for immunohistochemical markers of histiocytic lineage (CD68) and negative for those of melanocytic lineage (S100, HMB-45, Melan-A). This process is rarely described in lymph nodes. We present a report of a patient with melanosis involving multiple lymph nodes of an axillary dissection, done for metastatic melanoma with an unknown primary, and discuss possible prognostic and treatment factors.

Tumoral Melanosis in the Setting of Targeted Immunotherapy for Metastatic Melanoma—A Single Institutional Experience and Literature Review

“…Although most cases of tumoral melanosis have presented as cutaneous lesions, 1-3,6-13 2 cases of tumoral melanosis occurring in the lymph nodes have also been reported. 4,5 In our series, 1 patient was found to have tumoral melanosis in a lymph node identified during lymph node dissection, while the rest of the cases presented as dermal or subcutaneous lesions (Fig. 3).…”

“…Clinically, tumoral melanosis typically presents as blue, black, or purple macules, papules, patches, and nodules highly suspicious for primary melanoma or cutaneous metastases. [1][2][3][4][5][6][7][8][9][10][11][12][13]15 The Garrido et al 14 report was unique in that the tumoral melanosis presented as an erythematous, scaly plaque on the upper trunk. Because tumoral melanosis and melanoma cannot be distinguished clinically, histopathology along with the clinical history is essential to establish the diagnosis.…”

“…Tumoral melanosis represents a rare presentation of completely regressed melanoma with only 18 cases reported to date. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] There is limited guidance in the literature regarding diagnostic criteria for tumoral melanosis, and it is difficult to distinguish from partial regression.…”

“…Typically, histopathology of tumoral melanosis demonstrates a large, nodular collection of melanin-laden macrophages and melanin pigment in the dermis and/or subcutaneous tissue in the absence of melanocytes. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] Alternatively, regression typically displays additional features of fibrosis, lymphocytic inflammation, remaining viable melanocytes, and in some cases, a prior history of preceding melanocytic lesion. [16][17][18][19][20][21][22] Most recently, tumoral melanosis has been described in the context of immunotherapy with ipilimumab (a monoclonal antibody targeting CTLA-4) as well as nivolumab and pembrolizumab (humanized monoclonal antibodies against programmed death 1 receptor) and has been believed to be associated with improved prognosis.…”

Lymph Node Melanosis From a Primary Cutaneous Lesion Combining a Nodular (Tumoral) Melanosis and a Congenital Dermal Melanocytic Nevus

“…Tumoral melanosis involving also lymph node is an even rarer event that has been reported only twice in the literature. 3,4 We report a case of lymph node melanosis in the sentinel lymph node draining from a primary cutaneous lesion combining a dermal tumoral melanosis associated with an intradermal ''nevoid'' component consistent with a deep congenital nevus. We discuss the histopathological diagnosis of our primary cutaneous lesion and the sentinel lymph node microscopic findings, compare our case with the previous ones, and discuss the possible prognostic and therapeutic implications.…”