Unknown primary melanoma

Abstract

Of 230 melanoma patients treated during the past 8 years, 12 (5.2%) were found to have unknown primary lesions. Nine of these "unknown primary melanoma' patients presented with metastases in regional lymph nodes, one inside the parotid gland, and two presented with disseminated melanoma and no detectable primary tumor. The patients with melanoma confined to a regional lymph node underwent block dissection followed by adjuvant chemotherapy and immunotherapy. Four patients with metastasis in only one lymph node are disease free 4-6 years after diagnosis. One patient with multiple metastases in the groin is alive 8 years after lymphadenectomy. The other five patients with metastases in multiple regional lymph node died 16 months to 3 years after surgery. Both patients with disseminated melanoma succumbed to their disease within a month of diagnosis. The prognosis of unknown primary melanoma seems to be no worse than the typical melanoma at the same stage. This justifies the aggressive surgical approach to this unusual entity of melanoma.

Melanoma without a Detectable Primary Site with Metastases to Lymph Nodes

“…The prognosis for the analyzed group of patients with melanoma was no worse than that of other patients after excision of the primary tumor and regional lymph node metastases, although considerable variations were observed between studies 19–23 . Some series have reported better survival in patients with MUP and lymph node metastases 19,20 .…”

Completely regressed primary cutaneous malignant melanoma with nodal and/or visceral metastases: A report of 5 cases and assessment of the literature and diagnostic criteria

“…[26][27][28][29][30][31][32][33][34][35][36] The majority of these series excluded patients with any skin condition (''observed'' and/or ''removed''), [26][27][28][29][30] or implied exclusion of such patients through discussion of unremarkable skin examinations. [31][32][33][34] One series noted 8 of 40 cases to be metastatic melanoma from an unknown primary with a ''history of regressed skin lesions,'' but according to the report, no case actually demonstrated a ''clinically apparent area of regression,'' and histologic confirmation was lacking. 35 Another series documented 6 of 26 patients with metastatic melanoma from an unknown primary site and a ''history of spontaneous regression of a possible primary tumor,'' but absolutely no additional information was provided (age, location of lesion, extent of disease, specific histologic findings, or clinical course), thereby leading to exclusion.…”

“…69,70 Most large series of melanoma have documented a 4% to 10% incidence of metastatic melanoma with an occult primary lesion. [71][72][73] In many cases, occult primary malignant melanoma may be explained by complete regression of a primary lesion. Still others have observed rests of nevus cells within nodal tissue.…”

Novel Therapies for Metastatic Melanoma: An Update on Their Use in Older Patients

“…However, complete regression of primary cutaneous or metastatic melanoma remains a rare occurrence [105][106][107][108][109]. As 2.2-5.6 % of melanomas have no known site of primary origin [2,[110][111][112], the assumption is sometimes made that in these cases the primary site has undergone complete regression, possibly immunologically mediated, as the histological presence of lymphocytes could suggest. Interleukin-2, a cytokine that supports T-cell proliferation, was found to have a benefit in a small subset of melanoma patients [113,114], further suggesting a potential role of the immune system.…”