Microphthalmia transcription factor immunohistochemistry: a useful diagnostic marker in the diagnosis and detection of cutaneous melanoma, sentinel lymph node metastases, and extracutaneous melanocytic neoplasms.
BACKGROUND
Melanoma is the most lethal form of skin cancer. Diagnosis of amelanotic melanoma and detection of micrometastases in sentinel lymph nodes pose diagnostic and therapeutic dilemmas for the dermatopathologist and clinician.


OBJECTIVE
The purpose of this article is to determine the utility of immunohistochemistry using antibodies specific for microphthalmia in the identification of melanocytic lesions in the skin, eye, central nervous system, and sentinel lymph nodes.


METHODS
Paraffin-embedded, formalin-fixed specimens of cutaneous melanoma, including amelanotic melanoma and lentigo maligna melanoma, were stained with antibodies specific for microphthalmia. In addition, paraffin sections of extracutaneous lesions, including sentinel lymph nodes, uveal melanoma, and central nervous system melanocytomas, were stained with the specific microphthalmia antibody.


RESULTS
All cutaneous melanomas stained positively with microphthalmia, as did uveal melanomas and central nervous system melanocytomas. These findings confirm the melanocytic origin of melanocytomas and uveal melanomas and demonstrate that microphthalmia staining can be used to establish melanocytic origin of neoplasms. In addition, micrometastases were easily detected in sentinel lymph nodes.


CONCLUSIONS
Microphthalmia transcription factor immunohistochemistry is a valuable tool in the identification of melanocytic lesions in numerous sites. Use of this stain may facilitate detection of micrometastases in sentinel lymph nodes.
O'Reilly
F M
FM
Department of Dermatology, Emory University School of Medicine, 5309 Woodruff Memorial Bldg., Atlanta, GA 30322, USA.
Brat
D J
DJ
McAlpine
B E
BE
Grossniklaus
H E
HE
Folpe
A L
AL
Arbiser
J L
JL
D000912:Antibodies, Neoplasm; D014408:Biomarkers, Tumor / Q000276:immunology*; D001932:Brain Neoplasms / Q000175:diagnosis / Q000556:secondary; D004268:DNA-Binding Proteins / Q000276:immunology*; D005134:Eye Neoplasms / Q000175:diagnosis / Q000556:secondary; D006801:Humans; D007150:Immunohistochemistry / Q000592:standards; D008207:Lymphatic Metastasis; D008545:Melanoma / Q000175:diagnosis* / Q000556:secondary; D051739:Microphthalmia-Associated Transcription Factor; D016612:Paraffin Embedding; D012680:Sensitivity and Specificity; D012878:Skin Neoplasms / Q000175:diagnosis* / Q000473:pathology; D014157:Transcription Factors
D000912:Antibodies, Neoplasm; D014408:Biomarkers, Tumor; D004268:DNA-Binding Proteins; C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor; D014157:Transcription Factors