Vaginal Primary Malignant Melanoma : A Critical Update

Copyright: © 2014 Androutsopoulos G, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Vaginal primary malignant melanoma (VPMM) is a rare and very aggressive tumor [1,2]. It accounts for 0.3-0.8% of all malignant melanomas, 2-5% of female genital tract melanomas and less than 3% of all vaginal malignancies [1-3]. Only 250 cases have been reported in the English literature [1,2].

The precise pathogenesis of VPMM is relative unknown [9].Probably arises from melanocytes located aberrantly in vaginal epithelium [9,10].Those melanocytes can be found in the basal layer of vaginal epithelium in 3% of healthy women [11].It is thought that active junctional changes are the initial stage in malignant melanoma development [12].However, ultraviolet radiation is not the causal factor in VPMM [4].
Although there are several treatment options for patients with VPMM, an appropriate and effective treatment protocol has not defined yet [7].
Surgery remains the primary treatment of choice in patients with VPMM [2,7].The spectrum of surgery ranges from conservative (wide local excision) to radical (vaginectomy, pelvic exenteration) [2,7,15].If wide local excision with clear margins is possible, the role of radical surgery remains unjustified [2,7].If wide local excision is impossible, pelvic exenteration may be reasonable [2].
Lymph node dissection is not recommended in patients with VPMM, as the rate of lymph node metastasis is low [7].Moreover the role of elective lymph node sampling in those patients remains controversial [2,7].Although lymph node dissection has no survival benefits, it leads to significant morbidity [7,17].Recently, sentinel lymph node biopsy has gained popularity [7,18].
Radiotherapy in patients with VPMM, includes external pelvic radiotherapy and/or brachytherapy.It can be applied as primary treatment for patients who are unable or unwilling to have surgery [2,7,19,20].It can be applied preoperative, to reduce tumor size and enable a more conservative surgery [2,7,19,20].Also it can be applied postoperative as adjuvant treatment for patients with tumor size ≥ 3 cm, incomplete tumor resection or pelvic metastases [2,7,8,19,20].
For many years chemotherapy with dacarbazine (DTIC) is the standard of care in patients with advanced stage cutaneous malignant melanoma (CMM) [23].However, the role of chemotherapy in patients with advanced stage VPMM, has not been established [24].
The combination of chemotherapy and immunotherapy (biochemotherapy) in patients with advanced stage CMM, associated with an increased response rate [27].Although it clearly improves response rates, it has no survival benefits [27].Moreover, biochemotherapy has significant toxicity [27].However, the role of biochemotherapy in patients with advanced stage VPMM has not been established [30].
VPMM is a very aggressive tumor and most patients diagnosed at advanced stage [1,16,25,31].The extensive vascular and lymphatic network of the vaginal mucosa, contribute to early tumor spread and metastasis development [5,7,15].Despite treatment modality, 5-year survival ranges from 8.4-17.5% [1,5,7,10].Tumor size (<3 cm) is the most important prognostic factor [5]. Tumor thickness is only a weak predictor of survival [5].Many patients with VPMM have: local recurrences in the pelvis and distant metastases in the lungs, liver, bones and brain [5,9].Most of patients with distant metastasis also have a concomitant local recurrence in the pelvis [5].
It is obvious that the prognosis of VPMM is very poor despite treatment modality, as most cases diagnosed at advanced stage [1,8,16,25].Moreover its prognosis is much more unfavourable, compared with other vaginal malignancies and CMM [9].Especially in patients with no clear surgical margins and tumor size ≥ 3 cm, needed postoperative adjuvant radiotherapy.
Especially in elderly patients with bad performance status and comorbidities, we can apply high dose rate brachytherapy (HDRB) with Ir [8,21,22].It is well tolerated and associated with less side effects than external pelvic radiotherapy [8,22].