In contrast to leiomyomas, desmin
immunoreactivity is focal.
Leiomyoma is a benign lesion which stains positively for vimentin, smooth muscle actin and desmin
, similar to IMT.
Results for all other tested markers, including cytokeratin stains (Figure 9, B [inset]), CD45, ER, PR, HER2/neu, p63, and desmin
, were negative (Figure 9, C [inset]).
Immunohistochemical staining was diffusely positive for desmin
and smooth-muscle actin--findings consistent with a leiomyoma.
However, staining for desmin
, SMA and CD117 were negative.
Among these, p53 (7,8) and epithelial membrane antigen (9) are claimed to be indicators of malignancy, while desmin
is claimed to mark benign mesothelial cells.
Pathological analysis revealed a malignant spindle cell tumor with negative immunohistochemical staining for CD117 and CD10 and mild reactivity for desmin
and muscle specific actin, making low grade leiomyosarcoma the most likely diagnosis.
16,17) Immunohistochemistry can demonstrate antibodies to S-100, vimentin, smooth-cell actin, desmin
, CD34, and neuron-specific enolase.
The immunohistochemical expression (yes/no) of several markers was evaluated; these were vimentin, cytokeratin (CK), CD117, CD68, CD45, CD34, CD31, CD10, epithelial membrane antigen (EMA), desmin
, smooth muscle actin (SMA), Factor VIII, S100, Ulex europaeus agglutinin, I (UEA), carcinoembryonic antigen (CEA), actin, melan-A, HMB45 and vascular endothelial growth factor (VEGF).
Sections were immunostained with the ABC (avidin biotin-peroxidase complex) method, with primary antibodies directed toward smooth-muscle actin (clone 1 A4), desmin
(clone D33), neuron-specific enolase (NSE; clone H14), S-100 protein (polyclonal), and antihuman cytokeratin (clone 5D3).
Immunohistochemical analysis showed that the spindle stromal cells were positive for CD10 and vimentin, but negative for PSA, smooth muscle antigen, p53, desmin
, CD34, S-100, androgen receptor, estrogen receptor, and cytokeratins AE1/AE3.
(positive in reactive mesothelium) had a sensitivity of 83% and a specificity of 83%.