Immunohistochemical staining revealed that the tumor cells were immunoreactive for vimentin, HMB-45
, S-100, and Melan-A.
Immunoreactivity for vimentin, S-100 protein, and HMB-45
is regularly present, melanocytomas in contradistinction to meningiomas--being EMA negative.
Immunocytochemical staining with thyroglobulin and TTF-1 combined with melanocytic markers, for example MARTI (melanoma antigen recognized by T cells 1), HMB-45
(human melanoma black 45) (Figure 3, D), S-100 protein, and microphthalmia transcription factor (MITF), can be useful in these cases.
Markers of muscular differentiation (desmin, myogenin, MyoD1, and smooth-muscle actin) and melanocytic markers (S100-protein, HMB-45
, and melan-A) were negative.
Neoplastic cells were positive for S100, HMB-45
, and vimentin.
The histopathological diagnosis can be assisted by the use of immunohistochemical markers, such as HMB-45
(New Jersey), using the following antibodies; S100, Human Melanoma Black 45 (HMB-45
), vimentin, Melan A, factor XIIIa, and CD68.
Incisional biopsy of the left inguinal lymph node revealed metastatic round cell tumor which is immunohistochemistry positive for vimentin, S100, and HMB-45
. The immunophenotype is consistent with malignant melanoma (Figure 1).
demonstrates salient cytoplasmic immunoreactivity, supporting melanocytic phenotype (HMB-45
The cells showed a positive reaction for HMB-45
antigen [Figure 1]b.
The patient was diagnosed with PEComa following human melanoma black-45 (HMB-45
) monoclonal antibody expression and 2 mitoses under 50x magnification during pathological examination.