A review with an additional case: amelanotic malignant melanoma at mandibular gingiva.

The purpose of this review with an additional case is to evaluate the clinical, ultrasonographic and histopathological features of a rare case of Amelanotic Malignant Melanoma (AMM) at mandibular gingiva and to compare our case with other published AMMs at mandibular gingiva. A 52-year-old male patient with no systemic diseases was referred to our clinic with a soft tissue lesion at mandibular gingiva. Ultrasonographic examination was performed and a lesion with malignant features was observed. A periapical radiograph was taken to investigate bone destruction and biopsy was planned. Histopathological examination revealed AMM and a literature search was performed to congregate reports which were indexed in PubMed, ScienceDirect, and ResearchGate. Three AMM cases at mandibular gingiva were found. Doppler Ultrasound examination suggested bone destruction and a 1.8 cm × 0.6 cm soft tissue mass with well-defined borders and increased vascularity. Due to its hypervascularity, depth of invasion and destruction at the bone, the lesion was prediagnosed as a malignancy. Lack of melanin pigmentation caused the large immunohistochemical panel study. The tumour cells showed HMB45 and S100 positivity and they were negative with SMA, Desmin, CK1.3, and CK20. Routine ultrasound examination of all soft tissue lesions is very important for assessing features such as vascularity, bone destruction and depth of invasion to detect malignancy. Melanocytic-associated immunohistochemical markers are crucial for AMM diagnosis. © The Japan Society of Clinical Oncology 2020.