Diagnosis and behavior of juvenile rhabdomyosarcoma

Fetal Type Rhabdomyoma of the Soft Palate in an Adult Patient: Report of One Case and Review of the Literature

Rhabdomyoma is a rare benign tumor with skeletal muscle differentiation. Rhabdomyoma is further classified into cardiac, adult, fetal, and genital subtypes. Out of these, fetal type rhabdomyoma (FTR) is the rarest. Only a small number of cases have been recorded in the literature. FTR typically affects male infants and young children and occurs predominantly in the head and neck region. FTR is exceedingly rare in the adult, with less than 30 cases reported. The classic FTR is composed of primitive undifferentiated spindle cells with scant eosinophilic cytoplasm embedded in a myxoid stroma. Immunohistochemically, the tumor cells are positive for desmin, muscle specific actin, and myogenin. Awareness and proper recognition of this rare entity is of considerable importance to avoid misdiagnosis of embryonal rhabdomyosarcoma. In this study, we report one case of FTR in an adult patient and reviewed the literature about the clinical and pathologic presentation of FTR in the adult.

Rhabdomyosarcoma Presenting as Acute Hematologic Malignancy: Case Report and Review of the Literature

The authors describe a case of undifferentiated rhabdomyosarcoma from unknown primary site, presenting as an acute hematologic malignancy with generalized lymphadenopathy, extensive bone marrow involvement and clinical and laboratory features of disseminated intravascular coagulation. Such a peculiar behaviour is known for rhabdomyosarcoma but is rare and can be a serious diagnostic problem for the clinician and the pathologist. The importance of a large spectrum immunohistochemistry as first diagnostic approach to any undifferentiated small-cell malignant tumor is stressed, together with the knowledge of the different immunoreactivity patterns. Desmin, MS-actin and myoglobin are the most reliable markers of this type of myogenic sarcoma.

Hematologic masquerade of rhabdomyosarcoma

We present the case of a 12-year-old boy admitted with the diagnosis of acute leukemia, but found to have an infiltration of the marrow by an alveolar rhabdomyosarcoma (RMS) as determined by the cytogenetic demonstration of a t(2;13)(q25;q14). A primary tumor could not be found. With this case as a basis, we have tabulated features of all similar cases in the literature and discuss the possible optimal approaches to establishing the correct diagnosis in such patients.

Rhabdomyosarcoma of the urinary bladder and vagina: a clinicopathologic study with emphasis on recurrent disease: a report from the Kiel Pediatric Tumor Registry and the German CWS Study

Rhabdomyosarcomas (RMS) of the urinary bladder and vagina vary in their biologic and clinical behavior and require different types of treatment. Anatomically the two organs are close, and the reason for these differences in behavior is unknown. We investigated tumor specimens of 51 urinary bladder RMS and 14 vaginal RMS with regard to histologic subtype, growth pattern, differentiation, and proliferation morphologically and immunohistochemically. Recurrences and/or "second look" specimens from 15 patients after chemotherapy were compared with the primary tumors. Within the 65 specimens we found 31 "classical" embryonal RMS, 26 embryonal RMS of botryoid subtype (BRMS), 3 embryonal RMS of spindle cell subtype, and 5 alveolar RMS. BRMS is more common in the vagina (11 BRMS of 14 cases) than in the urinary bladder RMS (15 BRMS of 54 cases). Classical embryonal RMS with a polypoid (exophytic) growth pattern is associated with a more favorable prognosis (92% 10-year survival) than the same type with a diffuse intramural (endophytic) growth pattern (68% 10-year survival, p = 0.02). The proliferation rate was associated with the degree of differentiation, but neither showed a correlation with prognosis. A marked maturation after chemotherapy was seen in the majority of recurrences and SL specimens, associated with lowered proliferation activity. Two of 12 patients with recurrences showing chemotherapy-induced maturation died of the disease. In conclusion, we determined that polypoid embryonal RMS of both the urinary bladder and the vagina have a comparably good prognosis. This includes all botryoid RMS. The poorer prognosis of the group of urinary bladder RMS as a whole was caused by a high incidence of diffusely growing RMS, which have a less favorable prognosis than polypoid RMS. Maturation after chemotherapy occurs frequently in RMS. In contrast to the excellent prognosis reported in other studies, we had two patients with fatal outcome despite chemotherapy-induced maturation in the recurrences.

A re-evaluation of imaging criteria to assess aggressive masticator space tumors

PURPOSE

To evaluate the correlation between the gross imaging evidence of an aggressive masticator space (MS) tumor and the presence of such a MS malignancy.

MATERIALS AND METHODS

Thirty patients were identified retrospectively who had a malignancy that either arose in or metastasized to the MS, had pathologic verification of the diagnosis, and had magnetic resonance (MR) and/or computed tomographic (CT) images. Specifically evaluated was the presence or absence of gross imaging evidence of mandibular erosion and the integrity of the medial MS fascia as evaluated by a smooth margin between this fascia and the parapharyngeal space fat.

RESULTS

Of the 30 tumors, 28 were high-grade malignancies and 2 were histiocytoses. Of these, 5 had mandibular erosion and violation of the MS fascia, 19 had bone erosion with an intact fascia, 4 had neither bone erosion nor fascial violation (3 of these patients were under the age of 20 years), and 2 had fascial violation with no bone erosion.

CONCLUSIONS

In 76.7% of patients with a malignancy arising in the MS, on imaging the medial MS fascia was grossly intact. There were 4 patients with MS malignancy and neither violation of the medial MS fascia nor mandibular bone erosion. Thus, these imaging findings may not be good criteria to evaluate the presence of a high-grade MS malignancy, especially if the patient is under the age of 20 years, in which age group MS sarcomas are more likely to arise.

Histopathological classification of childhood rhabdomyosarcomas: relationship with clinical parameters and prognosis

To define a useful and prognostically relevant classification system for rhabdomyosarcomas (RMSs), tissue sections of 113 well-documented, protocol-treated cases were retrieved from the files of the Emma Kinderziekenhuis Amsterdam, the Netherlands, and reclassified by a panel of pediatric pathologists. The following subtypes were recognized: embryonal RMS (n = 66), alveolar RMS (including the solid variant) (n = 16), botryoid RMS (n = 11), embryonal sarcoma (n = 6), and spindle cell RMS (n = 5). Nine cases were classified as RMS not otherwise specified (NOS). The above-mentioned histopathological subtypes correlated significantly with survival (P = .005) in patients with nonparameningeal tumors. Indeed, the best prognosis was observed in patients with spindle cell RMS, embryonal sarcoma, and botryoid RMS (10-year survival rates of 80% to 86%). Patients with embryonal RMS had an intermediate prognosis (10-year survival rate of 55%) and patients with alveolar RMS fared poorly (10-year survival rate of 9%). Survival rate was poor in patients with a localized parameningeal tumor, irrespective of histopathological subtype (10-year survival rate of 33%). Furthermore, this study confirmed the known impact on prognosis of localization (P = .008) and tumor node metastasis (TNM) stage (P = .0005). Classification of RMS subtypes proved to be fairly well reproducible (kappa ranging from 0.47 to 0.85 and percentage of concordance ranging from 50% to 85%). The best agreement was noted in botryoid RMS and the worst in embryonal sarcoma. However, improvement of agreement was noted for the latter subtype during the consecutive classification sessions. In summary, this study shows the strong prognostic value of histopathological subtypes and parameningeal tumor localization.

Prostatic embryonal rhabdomyosarcoma in adults. A clinicopathologic review

Embryonal rhabdomyosarcoma of the prostate is a rare, highly malignant tumor that occurs predominantly in male infants and children, in whom it is the most common prostatic sarcoma. Six cases occurring in adults have been published, and the authors report three additional cases. The natural history is characterized by rapid growth, with the typical formation of large pelvic or abdominal masses, often leading renal failure due to bilateral ureteric obstruction. The tumor eventually disseminates widely, mainly to the lungs, bone, liver, and serosal surfaces, and unlike most other sarcomas, regional lymph node metastases are common. Combined modality therapy has resulted in marked improvement in survival rates and reduced surgical morbidity for children with these tumors. However, in adults the prognosis remains poor, with all patients dying of disseminated disease within 16 months of histologic diagnosis (mean survival, 8 months).

N-myc gene is amplified in alveolar rhabdomyosarcomas (RMS) but not in embryonal RMS

DNA from 13 (6 alveolar and 7 embryonal) childhood rhabdomyosarcomas (RMS) was examined to determine the incidence and prognostic relevance of N- and c-myc genes. Southern analysis showed 5- to 20-fold amplification of N-myc gene in 4 of 6 alveolar but in none of 7 embryonal RMS (p less than 0.04; Fisher's exact test). The number of children who died with multiple- and single-copy N-myc gene was 4/4 and 5/9 respectively (p greater than 0.05; Chi-squared test). There was no statistically significant correlation between N-myc amplification and age, gender, site, stage or survival time. There was no amplification or gross rearrangement of c-myc in any of the 13 RMS.

Soft tissue tumors in first year of life: a report of 190 cases

A comprehensive review of soft tissue tumors in children and adolescents disclosed the presence of 190 neoplasms in 183 patients, which were diagnosed in infants between birth and 12 months of age; these infants represented approximately 20% of our entire pediatric soft tissue tumor series. In excess of 75% of cases were pathologically benign with the hemangioendothelioma, lymphangioma, and fibromatosis-myofibromatosis constituting the majority of cases in this category. Fibrous histiocytoma and lipoblastoma were the other two benign entities. Congenital-infantile fibrosarcoma was considered a borderline tumor because of its infrequently manifested potential for metastasis; none of the 13 cases in the present study behaved in a malignant fashion. Embryonal rhabdomyosarcoma and peripheral primitive neuroectodermal tumor were the two principal types (17 of 27 cases) of malignant soft tissue tumors. In contrast to soft tissue tumors in the first two decades, those in the first year of life were more often benign despite their cellularity and presence of mitotic activity. Fibroblastic-myofibroblastic tumors were more frequent in this young age group, whereas neurogenic and myogenic tumors were relatively more common in children older than 1 year of age. The trunk and head and neck region were the preferred topographic sites rather than the extremities, which was the case in children beyond the first year of life.

Testicular carcinoma in situ associated with rhabdomyosarcoma of the spermatic cord

A 12-year-old boy had an embryonal rhabdomyosarcoma in the distal portion of the spermatic cord. The tumor partially surrounded the testis, infiltrated the testicular tunics and formed an intratesticular nodule near the rete testis. The unaffected testicular parenchyma exhibited the characteristic germ cells of carcinoma in situ. We describe an association between these 2 types of tumors.

Rhabdomyosarcoma in children: a histological and immunohistochemical study of 59 cases

Recent studies have suggested that rhabdomyosarcoma can be divided into favourable and unfavourable histology groups. Those subtypes comprising the unfavourable histology group are alveolar, monomorphous round cell and anaplastic rhabdomyosarcoma, with a favourable histology group of embryonal rhabdomyosarcomas. An immunohistological study was undertaken on 59 childhood rhabdomyosarcomas, using antisera to keratin, S100 protein, vimentin, desmin, myoglobin, and troponin T. Our results suggest that desmin is the single most useful antibody in the diagnosis of rhabdomyosarcoma and was expressed in all our cases. The expression of troponin T in the majority of embryonal rhabdomyosarcomas but not in the other histological types has prognostic implications.

Rhabdomyosarcoma of the oral and paraoral region

Oral rhabdomyosarcoma (RMS) was studied by analysis of eight such cases which presented over a 25-year period. Rhabdomyosarcoma was the fourth most common oral sarcoma (7.5%) from this period after osteosarcoma (32%), fibrosarcoma (19%), and chondrosarcoma (9%). In patients younger than 20 years, RMS was the second most common sarcoma (six cases) after osteosarcoma (ten cases). Combined analysis with 113 further cases documented in the literature showed the majority of cases (71.2%) were embryonal. The alveolar subtype was considered a distant second in frequency (12.3%) even though the pleomorphic subtype was apparently more common (16.4%). However, the pleomorphic cases were diagnosed before histologic criteria were established to discern this entity from other pleomorphic sarcomas and this data is probably unreliable. Site predilections were found for the soft palate, maxillary sinus and alveolus, posterior mandibular region, cheek and lip and possibly tongue. The gingiva and floor of mouth were uncommon sites. There was a predilection for occurrence in the first two decades with a decline in the third decade. Documentation of recent cases treated with a multidisciplinary approach indicated that lesions in the oral soft tissues have a good prognosis; 17 of 21 such cases showed no evidence of disease after a mean follow-up period of 7.2 years (SD = 4.4). In contrast, four of five cases in the posterior mandible resulted in death after a mean period of 1.1 years (SD = 0.3).

Histopathological classification of childhood rhabdomyosarcoma: a report from the International Society of Pediatric Oncology pathology panel

Five hundred thirteen soft tissue tumours of childhood referred to the International Society of Pediatric Oncology (SIOP) Rhabdomyosarcoma study have been reviewed. The period covered was from January 1975 to December 1983. Three hundred thirty-nine neoplasms were regarded as embryonal rhabdomyosarcoma. The histological diagnosis of all referred tumours is given, and a classification of rhabdomyosarcomas developed during the course of the study is described. The relationship between histological subtypes and aspects of clinical behaviour is presented. The classification is thought to be helpful in diagnosis and also in assessment of the likelihood of recurrence and/or metastasis of childhood rhabdomyosarcoma.

Chromosome 2 abnormalities (+Der 2) in two cases of childhood rhabdomyosarcoma

Chromosome analysis was performed in two cases of rhabdomyosarcoma (RMS): one embryonal RMS and one alveolar RMS. Analysis showed number and structural abnormalities of chromosome 2. The relationship between these findings and published reports of karyotypes from RMS is discussed.

Histological and immunohistochemical findings in experimental rhabdomyosarcomas. Comparisons between original tumors, tumor recurrences and allotransplants in nude mice

Cellular heterogeneity, a regular property of malignant neoplasms, can constitute the basis for phenotypic shifting in malignant tumors. A disturbance of the balanced interactions as happens as result of all therapy measurements between tumor cell subpopulations and between tumor and host offers the possibility to profound changes on the basis of cellular heterogeneity. As tumor model we used methylcholanthrene-induced murine rhabdomyosarcomas, which were allotransplanted into nude mice. The original as well as the allotransplanted sarcomas were submitted repeated operative tumor mass reductions, comparable to an insufficient tumor surgery in man. The histology and the cellular differentiation were evaluated by light microscopy and immunohistochemical marker expression (vimentin, desmin and myoglobin). Our findings document that primary tumors, their recurrences after incomplete tumor removal, and allotransplants inclusive of their surgically induced recurrences were histologically and immunohistochemically not identical in every case when compared with each other, but despite the experimental procedures they retained basic criteria necessary for the rhabdomyosarcoma diagnosis. Changes in sarcoma histology and cellular marker expression are not only reflected by dedifferentiation but can also comprise differentiation (maturation) processes. After artificial breakdown of intratumoral cellular interactions and tumor/host relations, unknown sarcoma inherent factors directed to retaining basic properties obviously preponderate, at least for the moment, over accidental new cell clones with differing phenotypic characteristics, which could be expected by cellular heterogeneity and would result in a markedly changed tumor.

Rhabdomyosarcoma of the nasopharynx a case with recurrence of tumour after 20 years

A case of embryonal (botryoid) rhabdomyosarcoma of the nasopharynx originally occurring in a two year old male, with late recurrence in the neck 20 years after treatment by combined surgery and radiotherapy is presented. The histological diagnosis of rhabdomyosarcoma, and the significance of late recurrence are discussed.

Alveolar rhabdomyosarcoma arising in the nasal cavity of a 3-year-old child

A 3-year-old girl had a large exophytic mass protruding from the nares, of seven months' duration. Routine microscopic studies demonstrated a tumor composed of solid sheets of small cells, with scattered foci lining alveola-like spaces. Immunohistochemical studies demonstrated the presence of desmin and myoglobin, and the absence of prekeratin, neuron-specific enolase, and leukocyte common antigen. These observations are consistent with the diagnosis of alveolar rhabdomyosarcoma.

Cytologic features of ascites in malignant fibrous histiocytoma of the colon

The cytologic features of ascitic fluid in a case of malignant fibrous histiocytoma (MFH) of the colon are described. At autopsy, two solid tumor masses were found around the ascending and transverse colon, accompanied by about 3,000 ml of ascites. Tumor cells had infiltrated diffusely into the outer layers of almost all of the gastrointestinal wall, simulating peritonitis carcinomatosa. Cytologic examination of the ascites revealed various kinds of tumor cells; short spindle-like cells, multinucleated giant cells, and round cells with an invaginated nuclear margin, forming small clusters. These cytologic findings were considered to be very useful in the diagnosis of MFH, especially in cytologic examinations of ascites.

Immunohistochemical study of rhabdomyosarcoma. Unexpected staining with S100 protein and cytokeratin

The immunohistochemical study of 60 cases of rhabdomyosarcomas made it possible to test eight different antibodies currently used in tumour pathology: i.e., antisera to vimentin, desmin, myoglobin, cytokeratin, epithelial membrane antigen, S100 protein, neurofilaments, and leukocyte common antigen. Vimentin was found in 58 cases (97 per cent), desmin in 49 cases (82 per cent), myoglobin in 23 cases (38 per cent), S100 protein in 7 cases (12 per cent), and cytokeratin in 3 cases (5 per cent). Other markers were negative. S100 protein was present in large round tumour cells with abundant eosinophilic cytoplasm (round rhabdomyoblasts), whereas cytokeratin was present in small tumour cells similar to those observed in rhabdoid sarcoma. This unexpected staining should become common knowledge for the correct interpretation of the immunohistochemical study of small cell tumours in the young.

Rhabdomyosarcoma with bone marrow metastasis simulating acute leukemia. Report of two cases

Rhabdomyosarcoma manifested as a systemic disease is very rare and cases showing diffuse metastasis in the bone marrow are most unusual. Recently we encountered two cases of rhabdomyosarcoma with diffuse bone marrow metastasis which were clinically manifested as acute leukemia. The first patient was a 15-year-old female, who was admitted in 1982 with pancytopenia and many large primitive cells in bone marrow aspirates, hematological malignancy being diagnosed. Thereafter the bilateral breasts showed rapid swelling and a biopsy specimen revealed the histological features of typical alveolar rhabdomyosarcoma. The primary site of the neoplasm remained undetermined during the course. At autopsy, it was disclosed that the neoplasm originated from the left thigh and showed generalized metastasis. The second patient was a 38-year-old man, who was admitted in 1986 because of a nasal polyp obstructing the nasal cavity, and persistent nasal bleeding. Peripheral blood samples showed leukoerythroblastosis and thrombocytopenia, and large primitive cells were found in bone marrow aspirates, so that hematological malignancy was initially diagnosed. A biopsy specimen of the nasal polyp showed proliferation of large round cells and electron microscopy demonstrated the ultrastructural features of rhabdomyosarcoma.

Rhabdomyosarcoma presenting with diffuse bone marrow involvement, hypercalcemia and renal failure

Rhabdomyosarcoma and other small round-cell neoplasms of infancy and childhood frequently involve the bone marrow. An unusual clinical presentation of diffuse bone marrow involvement as the sole manifestation of the disease represents a difficult diagnostic challenge. We report the case of an 18-year-old boy presenting with lower back pain, sternum tenderness, anemia, thrombocytopenia, leukoerythroblastic blood film, hypercalcemia, and renal failure. No solid tumor was found. A diagnosis of rhabdomyoblastic bone marrow metastatic involvement was initially suggested by the morphological picture, and later confirmed by the ultrastructural findings. Hypercalcemia and renal failure were controlled, initially, with furosemide and calcitonin. The patient was treated with intensive chemotherapy, including vincristine, actinomycin D, cyclophosphamide, and doxorubicin. A remission was achieved, lasting 5 months until relapse.

Leu-7 in small cell neoplasms. An immunohistochemical study with ultrastructural correlations

In an effort to delineate the distribution of the Leu-7 antigen in small cell neoplasms, 283 paraffin-embedded examples of such tumors were studied immunohistochemically. These included 125 malignant lymphomas, 94 neuroendocrine carcinomas, 13 adenocarcinomas, 14 squamous carcinomas, four malignant melanomas, six neuroblastomas, four nephroblastomas (Wilms' tumors), six primitive neuroectodermal neoplasms, three "Askin" tumors, ten Ewing's sarcomas, and four embryonal rhabdomyosarcomas. Histologic diagnoses were verified by the use of electron microscopic study or independent immunostains. Overall, 44% of small cell neuroendocrine carcinomas expressed Leu-7, whereas nonendocrine carcinomas were uniformly nonreactive for this determinant. All neuroblastomas yielded immunopositivity, as did three primitive neuroectodermal tumors, three rhabdomyosarcomas, two "Askin" tumors, one nephroblastoma, one Ewing's sarcoma, and one malignant melanoma. None of the small cell lymphomas were Leu-7 positive. These results suggest that Leu-7 is a specific neuroendocrine marker in cases of small cell carcinoma, but its sensitivity is lower than that of other "endocrine" determinants. Reactivity patterns for Leu-7 in other small cell tumors demonstrate no specificity for any given line of cellular differentiation. However, the shared expression of this antigen by neuroblastomas, neuroectodermal tumors, Ewing's sarcomas, and Wilm's tumors contributes further to the hypothesis that these neoplasms may be related histogenetically.

Actin typing of rhabdomyosarcomas shows the presence of the fetal and adult forms of sarcomeric muscle actin

We analyzed actin expression in two human rhabdomyosarcomas as well as in three rhabdomyosarcomas induced in rats by the injection of nickel sulfide. All five tumors exhibited appreciable amounts of the sarcomeric alpha-actin types, in line with their myogenic differentiation. The level of these actins was particularly high in the rat tumors, which according to morphological criteria, all showed a higher degree of differentiation than the human tumors. Interestingly, in both human tumors and in two of the three rat tumors, the level of the cardiac alpha-actin type was significantly higher than that of adult skeletal muscle alpha-actin. Taken together with the results of recent reports indicating that the cardiac alpha-actin type is a marker of embryonic and fetal skeletal muscle, our findings indicate that rhabdomyosarcomas express the embryonic sarcomeric actin isoform.

Common leukocyte antigen staining of a primitive sarcoma

A 4-year-old boy presented with symptoms of tracheal obstruction and was found to have a polypoid tracheal mass, which was studied by biopsy. Light microscopy showed a tumor composed of small cells with round to oval dark nuclei, clumped chromatin, one to two nucleoli, and small, variable amounts of indistinct pink cytoplasm. In other areas the tumor had a loose, spindle appearance, with some cells showing more elongated nuclei, and fibrillar pink cytoplasm consistent with strap cells. Cross striations were not found. Electron microscopy showed desmosomes and 7 to 10 nm cytoplasmic filaments forming dense bodies. The findings are most consistent with a primitive sarcoma, probably rhabdomyosarcoma. Immunoperoxidase with three monoclonal antibodies for common leukocyte antigen showed diffuse membraneous staining with fresh-frozen tissue. All other lymphocyte and monocyte marker studies were negative. We believe that this case of anticommon leukocyte antigen staining, a rhabdomyosarcoma, represents the first report of a false positive reaction with monoclonal antibody to common leukocyte antigen.

Embryonal rhabdomyosarcoma of the uterine corpus and cervix

Embryonal rhabdomyosarcomas of the uterus and cervix are rare tumors with a very poor prognosis historically. Adjuvant multidrug chemotherapy combined with local radiation therapy and/or surgery has resulted in markedly improved survival rates. Six patients with embryonal rhabdomyosarcoma of the uterus/cervix are reported, with a compilation of 28 additional patients from the literature. Nineteen of 24 patients (79%) treated with combination therapy were alive and well 4-147+ months (median 61 months) after diagnosis. The six cases from USC Medical Center and affiliated hospitals are all well 17-144 months (mean 95 months) after diagnosis. Analysis of the collected series indicates that extent of disease is an important prognostic factor. Adjuvant chemotherapy with vincristine, actinomycin D, and cyclophosphamide (VAC) improves survival. Initial therapy for embryonal rhabdomyosarcoma confined to the uterus/cervix should include radical hysterectomy, pelvic lymphadenectomy, and adjuvant chemotherapy with VAC. Pelvic radiotherapy should be employed for involved surgical margins or positive nodes. Advanced disease managed initially with chemotherapy and radiotherapy may allow subsequent curative extirpative surgery.

Cellular differentiation and prognosis in embryonal rhabdomyosarcoma. A report from the Cooperative Soft Tissue Sarcoma Study 1981 (CWS 81)

Sixty-four cases of embryonal rhabdomyosarcoma (eRMS) were investigated for cellular differentiation by light microscopy. Of these 64 cases 20 were studied by means of immunohistochemistry. Histologically, three subgroups could be distinguished: primitive (less than 10% rhabdomyoblasts), intermediate (10-50% rhabdomyoblasts) and well differentiated (greater than 50% rhabdomyoblasts) eRMS. Vimentin-positive cells predominated in the primitive eRMS. Intermediate eRMS showed large proportions of desmin-positive cells but vimentin containing cells were also numerous. Myoglobin could only be demonstrated in well differentiated eRMS. Primitive and well differentiated eRMS mainly occurred in the head and neck area, whereas intermediate eRMS were predominantly located in the abdomen. Stage III and IV tumours predominated in cases of primitive eRMS, whereas lower stages were noted in cases of intermediate and well differentiated eRMS. Response to chemotherapy, evaluated after seven weeks of treatment, was achieved in 10/15 (66%) cases of primitive, in 16/19 (84%) cases of intermediate and 5/5 cases of well differentiated eRMS. It is concluded from the current study that the three subgroups of eRMS differ not only by cytological differentiation but also by site of predilection, stage at time of diagnosis and response to chemotherapy.

Comparison of beta enolase and myoglobin as histological markers of rhabdomyosarcoma

A comparative study of beta enolase and myoglobin as markers of muscle differentiation in rhabdomyosarcoma was carried out, using an immunoperoxidase peroxidase antiperoxidase technique. Material from 26 cases of childhood rhabdomyosarcoma was studied and subdivided into embryonal and alveolar types. Positive cytoplasmic staining for beta enolase was seen in 85% of tumours studied (91% alveolar, 79% embryonal), whereas positive staining for myoglobin was detected in only 69% of tumours (82% alveolar, 64% embryonal). beta Enolase and myoglobin are useful in the histological diagnosis of rhabdomyosarcoma, and of the two, beta enolase seems to be the more sensitive.

Embryonal rhabdomyosarcoma: immunohistochemical characterization

A 15-year-old boy was referred to the ear, nose, and throat clinic because of a swelling in the upper premolar region. The initial diagnosis of a poorly differentiated soft-tissue sarcoma was made. Further immunohistochemical studies established a definitive diagnosis of embryonal rhabdomyosarcoma. The tumor cells coexpressed both desmin, the component of muscle type intermediate filaments, and vimentin, which is typically found in mesenchymal tissues. Such coexpression is found in the early stages of myogenic differentiation. Another cytoskeletal protein, actin, was also found in relatively high concentrations. These results suggested the possible use of antibodies to these cytoskeletal proteins as histogenetic markers for the diagnosis of poorly differentiated rhabdomyosarcoma.

Mesenchymal and muscle-specific intermediate filaments (vimentin and desmin) in relation to differentiation in childhood rhabdomyosarcomas

Twenty-one childhood rhabdomyosarcomas were divided into three groups on the basis of cytologic composition. The tumors in group P consisted entirely of primitive mesenchymal cells, whereas those in groups M and W were characterized by the additional presence of numerous round rhabdomyoblasts and strap cells, respectively. The tumors were studied for the universal mesenchymal intermediate filament vimentin, and for the muscle-specific intermediate filament desmin. Vimentin positivity, which tended to be more prominent in primitive tumor cells, was found in all tumors, whereas desmin was found especially in round rhabdomyoblasts and strap cells. Desmin-positive primitive cells were found only in groups M and W, not in group P. It was concluded that the differentiation from primitive mesenchymal cells to morphologically recognizable myogenic tumor cells is accompanied by an increase in desmin positivity and, presumably, a decrease in vimentin positivity. Moreover, the observations suggest the existence of a group of "committed" cells that are morphologically primitive, but desmin-positive. These cells might play an important role in the observed further differentiation of rhabdomyosarcomas under chemotherapy.

Small round cell neoplasms: can electron microscopy and immunohistochemical studies accurately classify them?

The answer to the question posed in the title, "Small Round Cell Neoplasms: Can Electron Microscopy and Immunohistochemical Studies Accurately Classify Them?", is obviously "yes"; but a qualified yes--generally yes, perhaps with expertise usually yes, but never just plain yes. Some cases certainly will defy the best attempts even of the most expert in the application of these "special" techniques. And embarrassing as it may be for those of us infatuated with the latest technology to admit, it is with the difficult case especially that old-fashioned technology so often must be depended upon. In his excellent recent appraisal of the role of a variety of special techniques in this application, Triche offers the following comment: "Overall, electron microscopy is probably the most universally useful of all diagnostic techniques other than light microscopy in round cell tumors." The data from our studies certainly point to the same conclusion. With each of the tumors, electron microscopy demonstrated itself to be more reliable than immunohistochemistry. Electron microscopy offers not only greater sensitivity and specificity, but also greater versatility. Immunohistochemistry allows hypothesis testing only. Electron microscopy, on the other hand, can provide answers even when the right questions are not being asked. For example, if a particular small round cell tumor under investigation happens in actuality to represent something other than the neuroblastoma which it is being considered (e.g., a granulocytic sarcoma, liposarcoma, Wilm's tumor, etc.), electron microscopy can reveal this fact, but a neuron-specific enolase stain cannot. Parenthetically, it should also be said that electron microscopy has proven particularly well suited to the examination of fine-needle aspiration specimens. The two spare many patients in our institution the need for a major operative procedure to establish a secure tissue diagnosis. Immunohistochemistry does have a role to play but it is, at least in our opinion, clearly secondary to that of electron microscopy. The concept of replacing electron microscopy with a battery of immunostains has often been advocated as an economic measure, but this argument begins quickly to lose its weight as the number stains included in the battery is increased to cover the diagnostic possibilities. Giving consideration to the capriciousness of some of these stains, there exists with this also an increasing possibility of a spurious or misinterpreted result leading to an errant diagnosis.(ABSTRACT TRUNCATED AT 400 WORDS)

Small cell tumours in childhood: a review

The past decade has seen significant advances in the treatment of childhood malignancies accompanied by appreciable improvement in survival rates. Treatment programmes have been largely formulated to meet the specific characteristics of individual tumours, as well as being based on the extent of disease presented at diagnosis. In selecting the most appropriate treatment protocol, accurate histological categorization of resected or biopsied tumour is thus of paramount importance. In the paediatric age range in which so many tumours lack differentiation as to present as, or mimic, other small cell tumours, routine methods are often insufficient to resolve problematic histology. A wide range of special techniques is now at hand to assist the pathologist with this problem and this review is an attempt partly to rationalize the application of available methodology. Of considerable importance also is a knowledge of the behavioural characteristics of this group of tumours, their prototypic histology, as well as the range of morphological variability.

An investigation of beta enolase as a histological marker of rhabdomyosarcoma

Sections from 21 tumours diagnosed as primary or metastatic rhabdomyosarcoma were stained for alpha and beta enolase. The cases were subdivided into embryonal and alveolar subtypes (38% and 62%, respectively). Positive cytoplasmic staining for alpha enolase was seen in all but one case, and cytoplasmic staining for beta enolase was seen in some cells in 18 of the 21 cases (86% of the total, 88% of the alveolar subgroup, and 85% of the embryonal subgroup). No cells stained positively for beta enolase in the control series of neuroblastomas, fibrosarcomas, Wilms' sarcomas, and an osteosarcoma. The results show that beta enolase is a sensitive marker of muscular differentiation in rhabdomyosarcoma.