Metastatic melanoma of the gallbladder: A case report and review of the literature

Abstract

A single case of symptomatic metastatic melanoma to the gallbladder, with roentgenographic findings of gallbladder disease, is presented. Review of the 12 previously reported cases of symptomatic metastatic biliary melanoma and of those reports of "primary" melanoma of the gallbladder reveals marked similarity between the two groups, with regard to relative size, pathologic description, number, and location of lesions. This, together with the finding of "junctional activity" in our case, leads us to believe that most if not all melanomas present in the gallbladder are metastatic deposits from a known, undetected, or regressed primary locus elsewhere. Surgical removal, even in the presence of disseminated disease, is a worthwhile palliative procedure.

Primary malignant melanoma of the gallbladder in dysplastic naevus syndrome

“…However, the existing controversies on the subject, mainly because of the lack of definitive objective criteria of primitivity, resulted in the questioning of many of the reported GPMMs [13,20], to the point that doubts about the possible occurrence of such a pathology have been repeatedly raised [14,20]. The reported presence of normal melanocytes in the gallbladder [4,13,23,29] supports the possibility of the existence of GPMMs [7].…”

“…These criteria are, however, very weak, especially if singly taken. In fact, secondary gallbladder melanomas can be polypoid [18] or produce single neoplastic masses [7,17] or intraepithelial spread, which results in a "junctional component" [7,20] and can be the only metastatic site [2]. Heath and Womack sustain the necessity of the simultaneous satisfaction of criteria 3-5, with the possible substitution of the latter with principle 1 [13].…”

“…However, this precedent is likely irrelevant since: (1) that melanoma was in situ and thus had a negligible risk of metastases [9],(2) the 8-year time lapse separating the two events, although not excluding a secondary localisation [5,17,20], is quite a long time span and (3) the patient's dysplastic naevus syndrome increases the risk of developing primary melanomas [16,25].…”

“…As a matter of fact, widely accepted objective criteria of primitivity are lacking. The proposed requirements for primitivity assessment [13,18] have been often criticised [14,17], so that many of the reported cases of primary malignant melanoma of the gallbladder have been questioned [13,20], and doubts about the possible occurrence of such a pathology have been raised [14,20]. Having established that melanoma is the neoplastic type most frequently responsible for metastatic involvement of gallbladder, accounting for over 50% of such events [7,20], and that about 15% of disseminated melanoma involve gallbladder [20], justifies this scepticism.…”

“…The proposed requirements for primitivity assessment [13,18] have been often criticised [14,17], so that many of the reported cases of primary malignant melanoma of the gallbladder have been questioned [13,20], and doubts about the possible occurrence of such a pathology have been raised [14,20]. Having established that melanoma is the neoplastic type most frequently responsible for metastatic involvement of gallbladder, accounting for over 50% of such events [7,20], and that about 15% of disseminated melanoma involve gallbladder [20], justifies this scepticism. The present paper is significant in this context, because it not only deals with a gallbladder melanoma that fulfils the main reported (although discussed) requirements for primitivity assessment, but also, for the first time, produces an objective evidence of primitivity, demonstrating at an ultrastructural level the presence of a double population of melanocytes: a typical one exclusively junctional and an atypical one both junctional and infiltrating the lamina propria.…”