Cellular blue nevus of the uterus: a case report and review of the literature

Melanoma arising in extracutaneous cellular blue nevus: report of two cases with comparison to cutaneous counterparts and uveal melanoma

AIMS

Blue nevi are benign melanocytic lesions that typically occur in the dermis. Melanoma arising in blue nevus is rare and shows a molecular profile distinct from conventional forms of cutaneous melanoma and more similar to uveal melanoma and central nervous system (CNS) melanocytomas. In contrast to conventional cutaneous melanoma, these tumor types typically show activating driver mutations in GNAQ or GNA11, a low mutational burden without evidence of a UV signature, and a reproducible pattern of chromosomal copy number changes. Blue nevi can also occur at extracutaneous sites. Here we report two cases of melanoma arising in extracutaneous blue nevus and compare their molecular features to cohorts of melanoma arising in cutaneous blue nevus (5 patients) and uveal melanoma (6 patients).

METHODS AND RESULTS

We describe the clinical, histomorphologic, immunohistochemical, and molecular findings in these two cases of melanoma arising in extracutaneous blue nevus. We compare their molecular profiles to melanomas arising in cutaneous blue nevus and uveal melanoma using a targeted next-generation DNA sequencing platform and find striking similarities between all three groups.

CONCLUSIONS

The close relationship between blue nevus-associated melanomas, regardless of their anatomic site, supports and validates the concept of melanoma arising in extracutaneous blue nevus and suggests that the two groups share common pathogenic mechanisms. The similarity of both groups to uveal melanoma in turn supports the close relationship between blue nevus-associated melanoma, uveal melanoma, and CNS melanocytoma, and their distinction from conventional UV-associated melanoma. These findings have important implications for prognosis and therapy.

Uterine Cellular Blue Nevus Arising in Mullerian and Pelvic Dendritic Melanocytosis: Case Report of a Rare Phenomenon to Be Distinguished From Uterine Melanoma

A 37-yr-old woman presented to the gynecology clinic with abnormal uterine bleeding in the setting of known, large uterine fibroids. Preoperative endometrial biopsy identified atypical melanocytic cells concerning for uterine melanoma. Care was transferred to the gynecologic oncology service for hysterectomy. Intraoperative findings included macular, blue-black pigmentation of the peritoneum of the bladder and cervix, which was resected and sent for frozen section, confirming melanocytic neoplasia. The hysterectomy revealed multiple tan leiomyomas up to 12 cm, and a distinct 3 cm black, incompletely circumscribed mass in the endomyometrium composed of bland spindled cells with delicate melanin granules. The tumor cells were positive for Sox-10, BAP1, and Mart-1 (Melan-A) and negative for PRAME, PD-L1, and BRAFV600E by immunostains. Microscopic elements of similar melanocytes and melanophages were found in the cervix and bladder peritoneum. Molecular analysis of the uterine tumor identified a GNA11 mutation but no TERT or BAP1 mutation. The uterine melanocytic tumor has characteristic findings of a cellular blue nevus arising in association with dendritic melanocytosis of Mullerian and pelvic tissues, a rarely seen benign phenomenon that should be distinguished from malignant melanoma of the upper genital tract.

Blue nevus-like and blue nevus-associated melanoma: a comprehensive review of the literature

BACKGROUND

Malignant blue nevus, blue nevus-associated melanoma and blue nevus-like melanoma are all terms used to describe malignant melanomas arising from, in association with, or resembling blue nevi. This review is aimed at summarizing the available literature to reduce the confusion surrounding this rare malignancy, and aid the surgeon in choosing further diagnostic or therapeutic measures.

METHODS

We conducted a search of Medline, Embase, Science Direct, Scopus and the Cochrane Library for all full text articles published in English that reported on a malignant melanoma arising from, in association with, or resembling a blue nevus.

RESULTS

We identified 91 cases that fit the criteria above. The mean age at diagnosis was 45 years, with a slight male predominance (males: 48; females: 43). Metastatic cases were reported in 55% (n = 50), of which 16 were metastatic at the time of diagnosis, 16 developed metastases within the first year and 18 within 5 years of initial diagnosis. The mean Breslow thickness was 6.8 mm at the time of diagnosis (n = 39).

CONCLUSIONS

The histological criteria for diagnosing this malignancy are very poorly defined, and may contribute to the substantial confusion surrounding the terminology. There is no consensus on which prognostic indicators predictive of outcome in 'conventional' malignant melanoma are applicable to blue nevus-like melanoma/blue nevus-associated melanoma. However, two larger case series have demonstrated a significant association between Breslow thickness (or largest tumour dimension when non-epidermal) and recurrence-free survival, as well as rate of local recurrence, but larger studies are needed to confirm this.

The spectrum of grossly visible pigmented lesions in the uterine cervix: a prospective study

Pigmented lesions of the uterine cervix (UC) have not been systematically studied in the literature. Over an 18-mo period, we prospectively investigated the histologic spectrum of all macroscopically visible pigmented lesions of the UC. The incidence of pigmented UC was 1.6% (33/2118). Histologic examination revealed 32 cases (97%) with a histologic correlate, of which 26 lesions were of melanocytic nature including 25 blue nevi (BNs) (81%) and 1 melanotic macule (3%). The nonmelanocytic lesions included 1 case of focal granulomatous vasculitis (3%), 2 biopsy site-associated reactive changes with hemosiderin-laden macrophages (6.4%), 1 case of hemorrhagic Nabothian cyst (3%), 1 hemangioma (3%), and 1 case of multinucleated giant cell reaction to dark black carbon-like material (3%). Women with UC BN (1.2% incidence) were mostly whites (13/25, 52%) with a mean age of 47.4 yr (range, 31-64 yr). The number and size of BN per UC, all located in the endocervix, varied between 1 to 3 and 0.1 to 2 cm (mean, 0.68 cm). UC BN exhibited 3 distinct morphologic patterns: (1) stromal melanocytic focus composed of fine spindle cells (9/25, 36%); (2) mixed pattern with fine spindle, plump spindle, and epithelioid cells (15/25, 60%); and (3) nevoid stage with epithelioid cells (1/25, 4%). In contrast, cervical melanotic macule was located in the squamous epithelium of the ectocervix and characterized by hyperpigmentation of the basal keratinocytes admixed with scattered slightly enlarged melanocytes. In conclusion, pigmented lesions of the UC are not as uncommon as reported and mostly benign in nature. Several cases may require deeper levels for their detection and to exclude the rare phenomenon of UC melanoma.

Amelanotic cellular blue nevus: an unusual iris localization

The authors describe the first case of eye amelanotic cellular blue nevus reported in literature and discuss the main differential diagnosis.

Coexisting malignant melanoma and blue nevus of the uterine cervix: an unusual combination

Malignant melanoma (MM) and blue nevi of the uterine cervix are an extremely rare neoplasm, probably derived from embryologic migration of melanocytes from the neural crest. MM displays aggressive behavior with a poor prognosis. We report the case of a 76-year-old postmenopausal woman abnormal vaginal bleeding. She underwent a hysterectomy and bilateral salpingo-oophorectomy with paraaortic-iliac lymphadenectomy. Histopathological and immunohistochemical studies were consistent with the diagnosis of MM and blue nevi in the uterine cervix. Although it is extremely rare, this case suggests that MM of the uterine cervix should be considered in the differential diagnosis of undifferentiated neoplasm. Early diagnosis is essential in order to warrant a better prognosis, although there are no cases of cure described.