The diagnostic utility of desmin. A study of 584 cases and review of the literature.

The diagnostic utility of several antibodies against desmin and their optimal staining conditions have not been systematically evaluated. Sections of paraffin-embedded tissues from 584 cases were stained with a monoclonal antibody against desmin (Clone DER 11 from DAKO), using an avidin-biotin-peroxidase technique. The results were tabulated and compared with those from previous reports. The following observations were made: (1) When pronase digestion was performed before staining, desmin was equally demonstrable in tissues fixed in formalin, Zenker's, Bouin's, or B5 fixative; however, desmin staining was lost or significantly diminished in tissues fixed in absolute ethyl alcohol. In contrast, when pronase was not used, a positive staining was demonstrated only in tissue fixed in absolute ethyl alcohol. (2) Positive staining was found in normal muscle (92 of 92 cases), leiomyoma (12 of 13), rhabdomyoma (6 of 6), rhabdomyosarcoma (31 of 31), leiomyosarcoma (18 of 26). (3) Desmin was never found in epithelia, normal mesenchymal tissue other than muscle, tumors stimulating rhabdomyosarcoma, and epithelial tumors. (4) A positive staining was documented in 1 tumor (a fibrous histiocytoma) of 42 benign predominantly spindle cell tumors and in 8 of 89 predominantly spindle cell sarcomas. (5) Desmin was never documented in myoepithelial cells but stained myofibroblasts in 2 of 12 examples of granulation tissue and in 29 of 67 samples containing tumor-associated desmoplasia. The authors' data on the diagnostic sensitivity and specificity of the evaluated antibody should improve the use of desmin in diagnostic pathology.

Malignant rhabdoid tumor of the vulva: is distinction from epithelioid sarcoma possible? A pathologic and immunohistochemical study.

Epithelioid sarcoma (ES) and malignant rhabdoid tumor (MRT) have heretofore been regarded as two separate clinicopathologic entities. However, they have some histologic similarities, and both represent histogenetic and phenotypic enigmas. This study reports the pathologic and immunohistochemical findings of four vulvar neoplasms occurring in young women that represented diagnostic dilemmas because of their similarity to both ES and MRT. Only one case had the classic histologic features of ES, whereas, in our opinion, the other three cases fulfilled the histologic criteria of MRT, despite the fact that two of the three cases were reported earlier as examples of ES. Neither electron microscopy nor immunohistochemistry has been found to be helpful in separating ES from MRT, mainly because they share several ultrastructural and immunophenotypic features. The behavior of these vulvar tumors--ours and the few published examples of ES--is generally aggressive, more in keeping with MRT than classic ES. We believe that some, if not most, putative ES of the vulva are in fact MRT, a neoplasm with an unfavorable prognosis.

Malignant rhabdoid tumour of the bladder with immunohistochemical and ultrastructural evidence suggesting histiocytic origin.

A malignant rhabdoid tumour of the bladder is reported from a girl aged 6. Detailed immunohistochemical and ultrastructural investigations provide evidence which suggests a histiocytic origin for this controversial neoplasm.

Cardiac rhabdomyoma. A case report with reference to atrial natriuretic peptide.

An autopsy case of cardiac rhabdomyoma in a male infant is reported. Many nodules of rhabdomyoma were present in all four cardiac chambers and were microscopically composed of ovoid, glycogen-laden cells and typical "spider cells". Atrial natriuretic peptide (ANP) was immunohistochemically demonstrated in both normal myocytes and rhabdomyoma cells of both atria, but not in normal myocytes and rhabdomyoma cells of both ventricles. Ultrastructurally, atrial specific granules were present in atrial rhabdomyoma cells and normal atrial cardiocytes, and these showed ANP immunoreactivity with protein A-gold technique. It could be said that the localization and intracellular distribution of ANP in this cardiac rhabdomyoma were closely similar to those of normal human heart. With regard to the presence of ANP, cardiac rhabdomyoma cells arising in atria seemed to differ from those in ventricles, although many tumor nodules occurred in both atria and ventricles. Furthermore, it seemed that cardiac rhabdomyomas could also be divided into two parts: 1) an atrial part with ANP, and 2) a ventricular part without ANP. Therefore, this study confirms the hypothesis that cardiac rhabdomyoma is a hamartoma rather than a true neoplasm.

Rhabdomyoma of the retroperitoneum. A report of a tumor with both adult and fetal characteristics: a study by light and electron microscopy, histochemistry, and immunochemistry.

An unusual benign tumor of skeletal muscle origin is described. The tumor was located in the left retroperitoneum of a newborn female. The tumor contained features of both an adult and fetal rhabdomyoma when studied by light and electron microscopy, immunocytochemistry, and histochemistry. This is the only report of this type of neoplasm in the literature.

Myoglobin, desmin and vimentin in ultrastructurally proven rhabdomyomas and rhabdomyosarcomas. An immunohistochemical study utilizing a series of monoclonal and polyclonal antibodies.

The present study is an immunohistochemical analysis utilizing a series of mono- and polyclonal antibodies to myoglobin, desmin and vimentin in smooth and striated control muscle tissues, 7 alveolar and 7 embryonal rhabdomyosarcomas and 1 adult and 1 fetal rhabdomyoma with ultrastructurally proven rhabdomyoblastic differentiation in all the tumors. Formaldehyde-fixed and paraffin-embedded tissue was used for the immunohistochemical analysis of all the tumors, while ethanol fixation was also used for the analysis of the control tissues. The staining for myoglobin with the poly- and monoclonal antibody used was positive in both formaldehyde- and ethanol-fixed skeletal and cardiac control muscle. Trypsin treatment abolished the positive staining when the monoclonal antibody was used. Both the striated and smooth control muscle tissues were positively stained by the antidesmin antibodies. The influence of the fixative that was used and the trypsin treatment depended on the antibody used and the type and origin of the muscle tissue. All the tumors were positively stained with the polyclonal antimyoglobin and 8/14 rhabdomyosarcomas and the 2 rhabdomyomas were positively stained with the monoclonal antimyoglobin. All the tumors were positively stained with the polyclonal and 3 of the 5 monoclonal antidesmin antibodies used. Well-differentiated tumor cells were usually positively stained for both myoglobin and desmin. There were small, poorly differentiated tumor cells in the rhabdomyosarcomas and the fetal rhabdomyoma which were positively stained for desmin, whereas very few or no such cells were positively stained for myoglobin. A varying number of mostly small, poorly differentiated tumor cells were positively stained for vimentin in 12 of 14 rhabdomyosarcomas and in the fetal rhabdomyoma. The study showed that one of the monoclonal antidesmin antibodies produced the most consistent result with a positive staining in all cases. The monoclonal antimyoglobin antibody, which is a specific marker of rhabdomyoblastic differentiation, is also considered to be of value, although it did not produce positivity in all cases. It remains to be shown whether desmin can help in the diagnosis of poorly or undifferentiated rhabdomyosarcomas without light- or electron-microscopic evidence of rhabdomyoblastic differentiation.

Adult rhabdomyoma: ultrastructure and immunocytochemistry.

Adult rhabdomyoma is a benign, highly differentiated tumor of skeletal muscle. We observed transverse tubules and triads beside myofilaments in a rhabdomyoma from the submandibular area of a 66-year-old woman. Several types of muscle cells were present. In one, mitochondria abounded; in another, muscle filaments predominated. Myoglobin was also detected in the tumor.