Primary gallbladder melanomas are extremely uncommon. In published reports of such occurrences, there is debate concerning the existence of this basic entity [1,2]. Wieting and Handi [3] recorded the first primary gallbladder melanoma in 1907, and Walsh [4] reported the first histologically verified case of primary gallbladder melanoma fifty years later. Since then, there have been further cases reported of primary melanoma of the gallbladder [1,[4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38]]. Metastatic malignant melanomas are much more common. Following the initial belief that these metastases are uncommon in the gastrointestinal tract (GIT), accumulating evidence suggests that they account for 15 % of gallbladder metastases [39]. Although gallbladder metastases are uncommon, malignant melanoma accounts for 50–60 % of them [6,28]. The most contentious issue is histogenesis, or the possibility of this basic entity. Ricci et al. [28] discovered melanocytes, both normal and malignant, in malignant gallbladder melanoma. In the scientific literature, only occasional cases of primary pulmonary gallbladder melanoma (PGM) have been reported, primarily as single case reports.

Melanoblasts are yet to be established in organs of endodermal origin [10], and because the gallbladder is an endodermal offshoot, melanoma is unlikely to emerge from this organ or other visceral structures. On the other hand, non-neoplastic melanoblasts are the result of melanin-producing cells migrating from the neural crest to endodermal derivatives during embryologic development, which explains the presence of melanocytes within their mucosa [1] and supports the possibility of developing primary melanomas at these sites [39]. Therefore, primary gallbladder melanoma is theoretically plausible [2,22]. Although primary melanoma of the gallbladder is still a controversial clinical entity, studies on this subject continue to accumulate [1,[4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38]]. As a result, there is currently little data on the clinical, pathological, and molecular characteristics of these tumors. We conducted a thorough assessment of recent literature with the goal of describing the clinical manifestations, pathological and diagnostic aspects, therapeutic options, and prognostic results observed in PGM patients.