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 and S-100.
(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).
(d)
HMB-45 demonstrates salient cytoplasmic immunoreactivity, supporting melanocytic phenotype (
HMB-45, 400x).
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.