Clinical investigation of amelanotic malignant melanoma in the oral region.
OBJECTIVE
Amelanotic oral malignant melanoma (AOMM) is a rare tumor that is difficult to diagnose. We studied the clinical and pathologic features of nine cases of this tumor to define diagnostic criteria and estimate prognoses for 2 different types of AOMM.


METHODS
Nine patients with 2 different types of primary AOMM were examined between 1970 and 2002. The histopathology of surgical specimens was studied, uncertain diagnoses were supported by immunohistochemical reactions, and electron microscopy and prognoses were reviewed retrospectively.


RESULTS
AOMM without radial growth phase may be particularly difficult to diagnose correctly without immunohistochemical assistance. Tumors consisted of a mixture of polygonal and spindle cells in different ratios in tumors with and without radial growth phase. The life span ranged from 3 months to 6 years 3 months, and all 9 patients died of the tumor. In 7 of the 9 cases, distant metastases were found.


CONCLUSIONS
AOMM without radial growth phase may be misdiagnosed as epulis or squamous cell carcinoma. Questionable lesions, particularly maxillary and palatal lesions, must be biopsied for histopathologic and possibly immunohistochemical examinations followed by rapid treatment. The prognosis of AOMM was poor.
Department of Oral Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan. ntanaka@sapmed.ac.jp
Nobuyuki
N
Tanaka
Masafumi
M
Mimura
Yutaka
Y
Kimijima
Teruo
T
Amagasa
D000368:Aged; D000369:Aged, 80 and over; D002294:Carcinoma, Squamous Cell / Q000473:pathology; D002423:Cause of Death; D002455:Cell Division; D003937:Diagnosis, Differential; D005260:Female; D005882:Gingival Diseases / Q000473:pathology; D005887:Gingival Neoplasms / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D018328:Melanoma, Amelanotic / Q000473:pathology* / Q000556:secondary; D008854:Microscopy, Electron; D008875:Middle Aged; D009062:Mouth Neoplasms / Q000473:pathology*; D011379:Prognosis; D012189:Retrospective Studies