|Ahead of print publication
Primary vaginal malignant melanoma: A rare entity with review of literature
Shailja Puri1, Sarita Asotra2
1 Consultant Pathologist, Department of Pathology, SRL Ltd, Shimla, HP, India
2 Department of Pathology, IGMC, Shimla, Himachal Pradesh, India
Consultant pathologist, Department of Pathology, SRL Ltd Shimla HP, Shimla, Himachal Pradesh
Source of Support: None, Conflict of Interest: None
Primary vaginal malignant melanoma (PVMM) is an extremely rare tumor of the female genital tract, accounting for only 3% of melanomas of the female genital tract and 0.3%–0.8% of all melanomas in females. Vaginal melanoma is a very aggressive tumor with a 5-year survival rate of 5%–25%. High incidence of recurrence, spread to regional lymph nodes, and distant metastasis are responsible for poor prognosis of PVMM. Grossly, amelanotic melanoma of the vagina may be mistaken for other primary vaginal malignancies. Differentiation of malignant melanoma from other primary vaginal melanomas is essential because of better prognosis of most of other vaginal malignancies as compared to melanoma. Despite having poor prognosis, early detection and early treatment of PVMM may improve the prognosis.
Keywords: Female genital tract, malignant melanoma, primary vaginal malignant melanoma
| > Introduction|| |
Malignant melanoma is a common and aggressive malignancy of the skin. Malignant melanoma is also known to occur in the mucous membrane lining of respiratory tract, gastrointestinal tract, and genitourinary tracts. These mucosal melanomas arise from resident melanocytes in the mucous membranes. The incidence of mucosal melanomas is low, accounting for 1% of all melanomas. Forty percent of all mucosal melanomas are amelanotic compared to <10% cutaneous amelanotic melanomas. Female genital tract is a rare site of malignant melanoma. Vulva and vagina are the most common sites for malignant melanoma in the female genital tract. Vaginal melanoma accounts for only 3% of all melanomas of female genital tract, 0.3%–0.8% of all melanomas in females, with an incidence of only 0.46 cases per one million women per year, and <250 cases are reported in literature to date. The prognosis of primary vaginal malignant melanoma (PVMM) is poor and 5-year survival is only 5%–25%. We present a case of PVMM for its rarity with review of literature.
| > Case Report|| |
A 65-year-old postmenopausal woman presented with chief complaints of something coming out of the vagina and vaginal discharge for 1 month. Vaginal examination showed a 3-cm growth arising from the posterior vaginal wall. The growth was friable and bled on touching. No other lesion was identified in the cervix or vulva. A clinical diagnosis of vaginal carcinoma was kept and biopsy was performed. The biopsy was fragmented and all soft-tissue pieces were submitted for histopathological examination. The biopsy showed malignant cells arranged in sheets, nests, and cords. The malignant cells were pleomorphic varying in shapes from oval-to-spindle to polygonal. The cells showed hyperchromatic nuclei, prominent nucleoli, intranuclear inclusions, and abundant eosinophilic cytoplasm [Figure 1]a. There were abundant mitotic figures and bi- and multi-nucleated giant cells. Possibilities of poorly differentiated carcinoma and amelanotic malignant melanoma were kept. Immunohistochemistry (IHC) showed that the malignant cells were immunoreactive of HMB-45 3+ [Figure 1]b, S-100 4+ [Figure 1]c, and melan A 3+ [Figure 1]d. In the absence of any other lesion in rest of the genital tract, a diagnosis of primary malignant melanoma of the vagina was signed out. The patient denied any further surgical intervention and was thus sent for radiotherapy. The patient did not show any evidence of relapse or metastasis after 6 months of radiotherapy.
|Figure 1: (a) Pleomorphic malignant cells showing hyperchromatic nuclei, prominent nucleoli, intranuclear inclusions, and abundant eosinophilic cytoplasm. (b) Immunohistochemistry showing malignant cells immunoreactive for HMB-45. (c) Immunoreactive for S-100. (d) Immunoreactive for melan A|
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| > Discussion|| |
PVMM is defined as melanoma originating in vaginal wall without involvement of the vulva and/or the uterine cervix. It is an extremely aggressive and rare malignancy accounting for only 3% of all vaginal malignancies. Studies have shown that it arises from melanocytes present in the basal layer of the vaginal epithelium. Mucosal malignant melanomas are known to initiate after junctional activity. Malignant melanoma can arise anywhere in vagina; however, anterior wall of the lower one-third part is the most common site. Most common presenting symptom is vaginal bleeding. Other less common presenting symptoms are vaginal discharge, vaginal mass, and pain. PVMM is polypoidal or nodular and often ulcerated. Pigmented lesions can be grossly identified as melanomas; however, nonpigmented lesions appear similar to vaginal epithelial tumors. The differential diagnoses include metastasis from other sites, poorly differentiated squamous cell carcinoma, sarcoma, lymphoma, and blue nevus. All histological variants – epithelioid, spindled, and mixed – are seen, epithelioid being the most common.
The natural course of malignant melanomas is marked by early local recurrence, extensions, metastases to lymph nodes, viscera, and also life-threatening hemorrhage, making it the most dangerous form of vaginal tumor. Extensions and metastases may be explained by the extensive lymphatic and vascular supply to the lamina propria of the vaginal mucous membranes. The common sites of recurrence of vaginal melanoma are vagina, vulva, and groin. Lymph node spread follows the lymphatic drainage of vaginal mucosa. Malignancies of upper third metastasize to external iliac nodes, middle third to the common and internal iliac nodes, and lower third to superficial inguinal and perirectal nodes.
The common sites of distant metastasis are the lungs, liver, bones, and brain. Tumor size (<3 cm) is the most important prognostic factor, whereas tumor thickness is only a weak predictor of survival. FIGO staging for vaginal malignant melanoma is not suitable because it does not incorporate tumor size and regional lymph node status. The diagnosis of mucosal melanoma is usually made on the basis of histology and IHC. Radiologic evaluation is important for the purposes of staging, operative planning, and monitoring of patients with metastatic disease undergoing systemic treatment. Computed tomography and positron emission tomography are of relatively limited value in local disease evaluation but are primarily used to detect clinically unsuspected metastatic disease.
The treatment modalities available are surgical and nonsurgical. Surgical modalities range from wide local excision to vaginectomy with or without vulvectomy. Wide excision may be wide radical excision or wide local excision where <2 cm circumferential margin is obtained because of difficult anatomic location of tumor. Studies have found that the recurrence rate and survival are similar in patients who have undergone of radical surgery and local excision. Recent data are in favor of conservative approach and radiotherapy. Thus, surgery may be combined with radiotherapy or chemotherapy in selected cases. Although a number of adjuvant chemotherapy regimens have been tested in the effort to reduce recurrence rate in high-risk melanoma, none of the agents, such as dacarbazine, used either alone or in combination proved beneficial in randomized clinical trials. Recently, the most promising results have been reported with interferon alpha, which has become the standard of care for patients with resected node-positive cutaneous melanoma. The prognosis of vaginal melanoma is very poor, regardless the treatment modality, because most cases are diagnosed at a late stage.
PVMM is a rare and an aggressive tumor with 5-year survival of 5%–25%. The cause of poor prognosis is risk of local recurrence and distant metastasis. The most accepted treatment of malignant melanoma of the vagina is surgery and postoperative radiotherapy.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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