Introduction
Primary oral mucosal melanoma (OMM) is a very uncommon entity that makes
up about 1-8% of all malignant melanoma and less than 0.5% of all oral
malignant tumors.1.2OMM arises from oral melanocyte
which seems to be part of the oral immune system.1.3
Maxillary gingiva and hard palate are the most common sites of primary
OMM. The tongue specifically is an infrequent site and represents less
than 2% of all oro-nasal melanoma cases. 4 To the
best of our knowledge regarding English literature review, about 30
cases of primary malignant melanoma of the tongue were reported.
OMM has different etiohistopathology, genetic mutation, and prognosis
compared to cutaneous malignant melanoma. The exact etiology of OMM is
still unknown. Although alcohol consumption, tobacco use, cigarette
smoking, and denture trauma are reported to affect the occurrence of
OMM.5.6 Most of them are thought to be De Novo. Oral
pigmentation precedes the development of malignant melanoma in about
one-third of the patients.4.7 However, the mechanism
of this transformation is not clearly understood
yet.8.9
Oral melanoma can manifest as a macule, plaque, or mass. Therefore, they
are very easy to diagnose clinically because of their appearance in
contrary to nasal mucosal melanoma which cannot detect or diagnose
easily due to their location. However, they are often asymptomatic and
connived or misdiagnosed as benign pigmented lesions until advanced
stages when they become ulcerative or hemorrhagic, or painful. Delayed
diagnosis can be one of the reasons for the poor prognosis of OMM.9
Early detection and treatment would improve the prognosis
significantly.10 The treatment modality of choice is
not well depicted due to its rarity and poor prognosis. Radical surgery
currently is the “gold standard” and main treatment of OMM. It can be
combined with neck dissection, depending on cervical lymph node status.
Non-surgical treatment options, like radiotherapy and medical therapy
(e.g., checkpoint inhibitors), can be used as adjuvant treatment
depending on stage.1 The size and depth of the tumor,
lymphovascular invasion(LVI), necrosis, polymorphic neoplastic cells,
lymph node involvement, and metastasis straightly affect the prognosis.11 The five-year survival rate of OMM is about
15–38% which is the lowest among other melanoma.3
Melanomas of the oral cavity and tongue are commonly found in patients
older than 40 years, and males are affected slightly more than females.10
The early asymptomatic phase and difficulty in gaining complete radical
excision with safe margins are two important factors that contribute to
a bad prognosis. Hence, consideration of malignant melanoma in the
differential diagnosis of pigmented as well as non-pigmented lesions of
tongue and oral mucosa is critical, regardless of the age of the
individual. The thorough clinical examination followed by
histopathological and immunohistochemical study in suspicious lesions is
imperative to rule out oral melanoma.
We present a rare report of a young woman with a recurrence of tongue
melanoma while on maintenance treatment with
imatinibR, who was treated by partial glossectomy with
submental flap reconstruction and adjuvant radiotherapy.