Rhabdomyosarcoma in childhood. An immunohistological analysis with myoglobin, desmin and vimentin

A retrospective immunohistological analysis of 64 rhabdomyosarcomas in children was performed using antibodies against desmin and in 35 cases against myoglobin. In addition a group of 12 undifferentiated tumours in which the differential diagnosis included rhabdomyosarcomas was studied. Rhabdomyosarcomas were desmin positive in 57 cases (89%), 28 cases of which showed positivity of undifferentiated small cells (44%). Myoglobin was positive in 23 cases (66%), but only one case showed positivity of undifferentiated small cells. The results show the limited use of myoglobin in the diagnosis of rhabdomyosarcoma, especially of cases with a low degree of differentiation. Three out of 12 undifferentiated tumours were desmin positive and were reclassified as rhabdomyosarcomas. In 49 rhabdomyosarcomas the investigation was complemented by the demonstration of vimentin. Vimentin was shown to be present in 27 cases in tumour cells (55%). Undifferentiated cells were positive in 26 tumours (53%) and rhabdomyoblasts reacted in 9 cases (18%). Coexpression of vimentin and desmin in some cases reflects a situation in rhabdomyosarcomas that aberrantly mimics skeletal muscle embryogenesis. In three cases desmin and vimentin positive globular inclusions were observed. It is suggested that their formation is related to dystrophic changes of contractile and cytoskeletal filaments. From the diagnostic point of view a high percentage of desmin positive cases makes desmin a successful marker for rhabdomyoblastic tumours. It is pointed out, however, that even immunohistochemistry may not contribute to solving the problem of undifferentiated tumours and that each case must be evaluated comprehensively.     

Alveolar and poorly differentiated rhabdomyosarcoma. A clinicopathologic, light-microscopic, ultrastructural and immunohistochemical analysis

Eighteen poorly differentiated, small and dark cell malignancies afflicting young individuals without light-microscopic evidence of a rhabdomyoblastic differentiation or a growth pattern characteristic of rhabdomyosarcoma were analyzed and compared with a series of 30 alveolar rhabdomyosarcomas of varying differentiation, where the diagnosis could be established light-microscopically. The study comprised clinical data, light and electron microscopy and immunohistochemistry, using a battery of mono- and polyclonal antibodies against intermediate filaments, myoglobin, epithelial membrane antigen, neuron-specific enolase, S-100 and leucocyte common antigen. All 30 alveolar rhabdomyosarcomas were positive for desmin, while a minority were positive for myoglobin, using monoclonal antibodies. In 8 of the 18 small and dark cell malignancies, support for a rhabdomyoblastic differentiation was obtained by a positive staining for desmin. In only 3 of these 8 cases was there ultrastructural evidence of rhabdomyosarcoma. The results of the investigation indicate that immunohistochemistry is a more useful tool than electron microscopy in the diagnosis of poorly differentiated rhabdomyosarcoma and that the criteria for the diagnosis of poorly differentiated rhabdomyosarcoma may need to be reformulated.     

小细胞恶性肿瘤MyoD1、myogenin的染色敏感性和特异性

目的：研究肌源性调节蛋白在小细胞恶性肿瘤病理诊断与鉴别诊断中的作用。方法：应用免疫组化S－法，对56例小细胞恶性肿瘤，包括19例的胚胎性横纹肌肉瘤、6例的腺泡状横纹肌肉瘤、3例的Wilm瘤、14例的Wwing肉瘤／PNETs、14例的神经母细胞瘤以及4例的多形性横纹肌肉瘤行MyoD1、myogenin、MSA、desmin,myoglobin和CD99染色标记，结果：MyoD1和myogenin阳性核染色分别见于21／29（72．41％）和20／29（68．97％）的横纹肌肉瘤。除多形性横纹肌肉瘤外，4例MyoD1与5例myogenin核染色阴性者没有重叠。3例Wilm瘤中2例幼年型MyoD1核染色阳性，而myogenin只有1例核染色阳性，另1例年型Wilm瘤二者染色阴性。14例的Ewing肉瘤／PNETs的14例的神经母细胞瘤未见核阳性染色，MyoD1和myogenin核阳性染色与横纹肌肉瘤的分化程度呈负相关，在较小的原始肿瘤细胞中，MyoD1和myogenin核染色比较较高，而具有骨骼肌分化的，较大的横纹肌母细胞核阳性染色比例较低，在横纹肌肉瘤中，MyoD1阳性核染色的肿瘤细胞比myogenin多，myogenin多在小的肿瘤细胞核上染色，而MyoD1无论小的原始肿瘤细胞或是稍大的具有骨骼肌分化的肿瘤细胞均有不同程度的表达。MSA、desmin和myoglobin在小细胞肿瘤中染色的敏感性较低；结论：对于小细胞横纹肌肉瘤的诊断与鉴别诊断。MyoD1和myogenin是两种高敏感性和高度特异性的抗体，当疑为胚胎性横纹肌肉瘤或腺泡状横纹肌肉瘤时，应使用一组抗体，包括MyoD1、myogenin、MSA、desmin、myoglobin等有助于诊断。     

Sarcoplasmic reticulum (SR) Ca2(+)-ATPase as a marker of muscle cell differentiation: immunohistochemical investigations of rhabdomyosarcomas and enhancement of the immunostaining after sodium methoxide pretreatment.

An immunocytochemical investigation of sarcoplasmic reticulum (SR) Ca2(+)-ATPase (SR-Ca-ATPase) was performed on formalin-fixed paraffin-embedded specimens of different types of rhabdomyosarcomas such as variants of embryonal and pleomorphic forms. Immunostaining frequency of tumours using SR-Ca-ATPase was compared with that of traditionally used muscle specific markers myoglobin, and desmin. Utilizing the possible cleaving of ester bounds sodium methoxide pretreatment was found to be very effective in enhancement of SR-Ca-ATPase immunostaining reaction. In 11 of 15 tissue specimens of 5 cases round shaped and elongated rhabdomyoblasts with definite cytoplasm exhibited positive immunoreactions with all of the polyclonal antibodies tested, using the streptavidin-biotinylated peroxidase complex (S-ABC-method). In formalin-fixed and paraffin-embedded material of 2 cases of undifferentiated rhabdomyosarcomas composed of small round tumour cells with scanty cytoplasm pretreatment with sodium methoxide induced the immunostaining of SR-Ca-ATPase. After that pretreatment a staining of the paranuclear cytoplasm occurred in many of these undifferentiated tumour cells. In these 2 cases, neither myoglobin nor desmin antibodies could react. However, when frozen sections of one of the poorly differentiated tumours were used monoclonal and polyclonal desmin antibodies reacted immunocytochemically in all of the small cells. Sodium methoxide induced or enhanced SR-Ca-ATPase immunocytochemical reaction can be a further addition to the diagnosis of rhabdomyosarcomas in formalin-fixed paraffin-embedded sections, even when desmin antibody fails to react.     

Expression of actin isoforms and intermediate filament proteins in childhood orbital rhabdomyosarcomas

The diagnosis of orbital rhabdomyosarcoma (RMS) in childhood gives rise to several clinical and anatomo-pathological problems. Antibodies recognizing structural proteins and cytoskeletal components have been shown to increase the diagnostic accuracy of different neoplastic lesions. In this study we examined anatomo-clinically and, where possible, by means of immunohistochemistry and electron microscopy, a series of 14 cases of orbital RMS in childhood. In the 12 cases studied by immunohistochemistry, desmin was always present, although showing variable patterns, and alpha-sarcomeric actin was found in 10 cases. alpha-Smooth muscle actin was always absent. The other markers tested (myoglobin, polyclonal actin, vimentin and enolase) proved unreliable for several reasons. We conclude that antibodies against desmin and alpha-sarcomeric actin are useful for the diagnostic definition of RMS. In addition, immunohistochemical analysis supplies data regarding the degree of tumor differentiation and may be applied to monitor radio- and chemotherapy.     

Sarcomas of the uterus: immunohistochemical characterization and diagnosis]

Pathologic findings and immunohistochemical characterizations of 18 cases of uterine sarcomas were studied. In endometrial stromal sarcoma (ESS), 5 out of 10 cases had ovarian sex cord-like pattern and 4 out of 10 cases had smooth muscle differentiation. Immunohistochemical findings showed vimentin, desmin and cytokeratin positive in 9/10, 6/10, 2/10 cases respectively which reflects that ESS may differentiate into both epithelium and muscle components morphologically. In malignant mixed Mullerian tumors (MMT), its carcinomatous structure may be positive about vimentin, and its sarcomatous structure may be positive to the epithelium markers, which indicates that both the sarcoma and carcinoma structures have possibly a common origin. It is considered to be of value for the diagnosis of MMT, if the tumor has differentiated both epithelium and mesoderm components or to be positive to myoglobin, NSE* in immunoreaction, accompanying with the morphologic characterizations of the tumor.     

Expression of cardiac ankyrin repeat protein, CARP, in malignant tumors: diagnostic use of CARP protein immunostaining in rhabdomyosarcoma

Cardiac ankyrin repeat protein (CARP) is highly expressed in cardiac muscles and detectable in normal skeletal muscles. Arpp, a close homolog of CARP, has been demonstrated to be useful for distinguishing rhabdomyosarcoma from other malignant tumors. However, the CARP distributions among malignant tumors have been poorly investigated. Here, we analyzed the comprehensive expression of CARP in malignant tumors and evaluated its potential use for rhabdomyosarcoma diagnosis. A total of 159 malignant tumors, including 34 rhabdomyosarcomas, 85 non-rhabdomyosarcomas, and 40 carcinomas, were immunohistochemically analyzed for CARP expression. Cytoplasmic expression of CARP was detected in 29 (85%) of 34 rhabdomyosarcomas. The immunoreactivity was observed in both small cells with little differentiation and differentiated tumor cells with abundant eosinophilic cytoplasm. In contrast, focal immunoreactivity for CARP was only observed in 5 (4%) of 125 non-rhabdomyosarcomas, comprising 2 malignant fibrous histiocytomas, 1 angiosarcoma, 1 epithelioid sarcoma, and 1 squamous cell carcinoma of the lung. Comparative analysis of the CARP expression profiles with those of myogenic markers in rhabdomyosarcomas revealed that myogenin (88%) and desmin (88%) exhibited the best sensitivity, followed by CARP (85%), MyoD (82%), muscle-specific actin (79%), and myoglobin (65%). MyoD (96%) and myoglobin (96%) had the best specificity, followed by CARP (95%), myogenin (95%), desmin (89%), and muscle-specific actin (86%). Our results indicate that CARP is a sensitive and specific marker for rhabdomyosarcoma and that it will be useful for the differential diagnosis of rhabdomyosarcoma.     

Diagnostic application of immunohistochemistry in pleomorphic sarcomas

Eighteen cases of pleomorphic sarcoma diagnosed or supposed as rhabdomyosarcomas (RMS) and fourteen cases of other soft tissue lesions were stained with five specific antisera (myoglobin, desmin, alpha-1-antitrypsin, Lysozyme, and S-100) by peroxidase antiperoxidase method. The immunohistochemical findings indicated that the majority of the pleomorphic sarcomas (11/18) had to be reclassified as malignant fibrous histiocytoma (MFH), and pleomorphic RMS was indeed rare in adults over the age of 30 years. In this MFH group, desmin was present in all but 3 cases (8/11), supporting that MFH is a tumor originated from mesenchymal cells other than histiocytes. The success of using immunohistochemistry for making pathologic diagnosis depends upon rational application of panels of antibodies. The diagnostic features of pleomorphic sarcomas in routine or special stains are discussed.     

Expression of desmin and myoglobin in rhabdomyosarcomas and in developing skeletal muscle

Immunohistochemical staining for desmin and myoglobin was investigated in 35 rhabdomyosarcomas from young people and in skeletal muscle from 16 human fetuses of known gestational age. Twenty-nine of the rhabdomyosarcomas expressed desmin but six undifferentiated or poorly-differentiated tumours were desmin negative. Of the desmin positive cases, most undifferentiated or poorly-differentiated sarcomas expressed desmin alone (12/35). Tumours with increasing rhabdomyoblastomic differentiation co-expressed myoglobin (9/35) and well-differentiated examples also contained cross-striations (7/35). Skeletal muscle from fetuses aged 8 weeks or less consisted mainly of primitive desmin negative round cells. As the cells began to differentiate they quickly expressed desmin and, at approximately 10 weeks, myoglobin was expressed and cross-striations were seen. The combined results strengthen the view that desmin (within a strictly defined context of round cell tumours in young people) is a reliable marker for rhabdomyoblastic differentiation. Support is also given to the notion that very primitive rhabdomyosarcomas may be desmin-negative, although the difficulties of establishing firm diagnoses for some of these tumours is emphasized.     

Clear cell sarcoma of the kidney. An immunohistochemical study

Three cases of clear cell sarcoma of the kidney (CCSK) and 5 cases of Wilms' tumor were investigated immunohistochemically to examine the expression of tissue-specific intermediate filaments (cytokeratin, vimentin, and desmin) and myoglobin. In CCSK, tumor cells were negative for cytokeratin, except for occasional tubular structures, and vimentin was demonstrated in only one case. In Wilms' tumor, epithelial components were positive for cytokeratin and stromal cells were positive for vimentin, while no staining was found in blastemal cells for either. Both desmin and myoglobin were negative in all tumor cells except for skeletal muscle cells in Wilms' tumor. In the current study, some neoplastic cells in CCSK were revealed to be of mesenchymal nature, but blastemal cells in Wilms' tumor were not.