ROSARIO SANTOS RIVERA
Department of Oral Pathology and Medicine
Graduate School of Medicine,
Dentistry and Pharmaceutical Sciences
Okayama University, Okayama City, Japan
E-mail: rsrivera@rocketmail.com
Affiliations:
Graduate School Scholar (October 2003 – present)
Department of Oral Pathology and Medicine
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences
Okayama University, Okayama City, Japan
Instructor (November 1995 – October 2003, on study leave)
University of the East
College of Dentistry, Manila, Philippines
Post-graduate trainings:
Visiting Researcher (December 1998 – June 1999)
First Department of Oral and Maxillofacial Surgery
Aichi-Gakuin University, Nagoya City, Japan
Extern (January – June 1994)
Department of Hospital Dentistry (Oral Surgery)
University of the Philippines – Philippine General Hospital
Manila, Philippines
Clinicopathological Evaluation of Oral Mucosal Melanoma
Rosario S. Rivera1, 2, Hitoshi Nagatsuka1, Chong Huat Siar3, Sandy Uy2, Patricia
Monica Lee2, Mehmet Gunduz1, Ryo Tamamura1 and Noriyuki Nagai1
1Department of Oral Pathology and Medicine, Graduate School of Medicine,
Dentistry and Pharmaceutical Sciences, Okayama University
Okayama City, Japan
2University of the East, College of Dentistry, Manila, Philippines
3Department of Oral Pathology, Oral Medicine and Periodontology, Faculty of
Dentistry, University of Malaya, Malaysia
Pigmented lesions in the oral cavity may be classified as melanocytic and
non-melanocytic lesions. It is necessary to distinguish pigmented lesions based
on this classification to rule out malignancy associated with transformed
melanocytes. Oral mucosal melanoma (OMM) is an extremely rare neoplasm
representing 1% of the melanomas and 0.5% of oral malignancies but a
formidable and fatal melanoma type due to steadfast invasion, growth,
proliferation and metastasis. The neoplasm is more common in Japan and Africa
than in Western countries. The poor prognosis compared to skin melanoma, with
a 5-year survival rate of about 15%, may either be due to its aggressive behavior
or the delay in diagnosis. OMM upon presentation most like involves the lymph
nodes and histopathologically is characterized by the invasion of tumor cells in
the underlying connective tissue (invasive OMM). Etiologic factors and precursor
lesions have not been clearly understood due to the lack of understanding of this
rare neoplasm. The biological significance of melanocytic tumors and of
pigmented lesions in general depends on their relationship to OMM. Most benign
melanocytic lesions are unimportant, but others may have significance as benign
stimulants of melanoma, as potential precursors of melanoma, or as markers of
risk for melanoma.
The study presents the clinical and histopathological evaluation of oral melanotic
macule, oral nevus and OMM. Distinguishing features between non-neoplastic
and neoplastic features will be presented. Moreover, the histological evaluation
of equivocal brown pigments (whether melanin pigments or hemosiderin
granules) with bleaching method, Iron detection and Fontana Masson will also
be discussed. Analysis of melanocytic differentiation markers such as S100,
HMB-45 and Melan A and proliferation index (Ki-67) will also be discussed.
Melanocytes are generally found in oral mucosa but may be unnoticed because
of their relatively low level of pigment production. However when they are focally
or generally active in pigment production or proliferation, they may be
responsible for several pigmentations of the mucous membrane ranging from
physiologic to malignant neoplasm. For these reasons, the distinction between
melanocytic from non-melanocytic lesions challenges every clinical practitioner
to detect these pigmentations and determine those lesions necessary for
histopathological evaluation and for pathologist to clearly identify the lesions.
Precise clinical and histopathological evaluation of pigmented lesions will aid in
the early detection and management of this fatal malignant melanocytic
neoplasia.