Abstract
We report a case of dermal malignant melanoma that stained negatively for commonly done immunostains, HMB-45, and Melan-A. It stained weakly positive for S-100 protein, a less specific marker for melanocytes. The diagnosis was established by strongly positive immunostaining by MITF ( microphthlmia-associated transcription factor). A brief review of the MITF and its usefulness in the diagnosis of melanoma are presented.
DOWNLOAD: Diagnostic dilemma
| The Internet Journal of Dermatology Volume 5 Number 1 |
| Diagnostic dilemma: HMB-45 and Melan-A negative tumor, can it be still a melanoma?: MITF (Microphthalmia- associated transcription factor) stain may confirm the diagnosis |
J Wang, D Sarma, P Ulmer
Citation
J Wang, D Sarma, P Ulmer. Diagnostic dilemma: HMB-45 and Melan-A negative tumor, can it be still a melanoma?: MITF (Microphthalmia-associated transcription factor) stain may confirm the diagnosis. The Internet Journal of Dermatology.2006 Volume 5 Number 1.
Abstract
We report a case of dermal malignant melanoma that stained negatively for commonly done immunostains, HMB-45, and Melan-A. It stained weakly positive for S-100 protein, a less specific marker for melanocytes. The diagnosis was established by strongly positive immunostaining by MITF ( microphthlmia-associated transcription factor). A brief review of the MITF and its usefulness in the diagnosis of melanoma are presented.
SOURCE OF SUPPORT
None
CASE REPORT
An 82-year-old male presented with a 1-cm raised dermal nodule on the medial side of the right foot that has been present for unknown duration. There was no pigmented lesion of the skin. The patient denied any previous history of melanoma.
The biopsied skin measured 1.8x 1.4 x 1.0cm and showed a well-circumscribed white, firm dermal nodule. The epidermis was intact.
On microscopic examination, the tumor mass was composed of large dysplastic epithelioid and spindle cells forming nests and sheets. The cell nests were surrounded by thin bundles of collagen. The tumor cells contained large, hyperchronic nuclei with prominent red nucleoli. There were many mitotc figures. There was no ulceration or epidermal invasion by the tumor cells. The lesion extended from papillary to deep dermis (Figures 1, 2).
Figure 1
Figure 1: Malignant melanoma, H&E, 4x
