Tumors of skeletal muscle

Off the wall: incidental paraspinal and pelvic muscle pathology on abdominopelvic imaging

As the use of cross-sectional abdominal and pelvic imaging has increased exponentially in the past several decades, incidental musculoskeletal findings have become commonplace. These are often unrelated to the indication for the examination and are frequently referred to as the "radiologist's blind spot" on these studies. The differential diagnosis for abnormalities of the paraspinal and pelvic musculature is, in many cases, quite different from the anterior abdominal wall muscles. Furthermore, due to their relatively deep location, pathology involving the former muscle groups is more likely to be clinically occult, often presenting only incidentally when the patient undergoes cross-sectional imaging. Effective treatment of diseases of these muscles is dependent on adherence to a diverse set of diagnostic and treatment algorithms. The purpose of this review article is to familiarize the radiologist with the unique pathology of these often-overlooked muscles of the abdomen and pelvis.

An extremely rare case of primary alveolar rhabdomyosarcoma in the central nervous system

Background

Alveolar rhabdomyosarcoma (ARMS) shows a predilection for the peripheral extremities and is very rarely identified as a primary in the brain. Here, we report a case of ARMS with multiple lesions exclusively within the central nervous system (CNS).

Case Description

A 20-year-old man presented to our hospital with a gradually increasing headache and disturbance of consciousness. Neuroimaging showed hydrocephalus and multiple tumor lesions, including in the brainstem and cerebellum, with uniform gadolinium enhancement on T1-weighted magnetic resonance imaging, as well as spinal cord seeding. Cerebrospinal fluid (CSF) analysis showed a slightly elevated cell count (6/μL; normal, <5/μL) and highly elevated protein (153 mg/dL). In addition, atypical cells were cytologically identified in the CSF. No other laboratory findings were abnormal. Emergency ventricular drainage was performed to control cerebral pressure, followed by a biopsy to confirm the diagnosis. Histological examination revealed a fascicular arrangement of oval cells with eosinophilic cytoplasm and tumor cells with pleomorphic nuclei and prominent nucleoli. Immunohistochemical studies showed negative results for glial fibrillary acidic protein and positive results for desmin and myogenin. In addition, molecular analysis revealed that this tumor had the H3F3A p.Lys28Met mutation and no paired box (PAX)3-forkhead box O1 (FOXO1) or PAX7-FOXO1 fusion genes. ARMS was, therefore, diagnosed. Chemotherapy and radiotherapy were subsequently initiated, but tumor growth could not be controlled, and the patient died 6 months after surgery.

Conclusion

This report describes an extremely rare case of ARMS arising exclusively within the CNS.

Benign mesenchymal tumours of the tongue: A report of adult-type rhabdomyoma and granular cell tumour with a review of the literature

The cytomorphological features of benign mesenchymal tumours of the tongue have rarely been reported. Herein, we present the cytomorphological features of adult-type rhabdomyoma, which occurred in the tongue of a female patient, and granular cell tumour (GCT), which occurred in the tongue of a male patient; both patients were in their mid-50s. The cytological features of the adult-type rhabdomyoma case included large polygonal to ovoid cells with abundant and granular cytoplasm with predominantly peripherally located, uniform, round to oval nuclei and small nucleoli. Cross-striation and crystalline intracytoplasmic structures were not seen. The cytological features of the GCT case included large cells with abundant granular pale cytoplasm, small round nuclei and small distinct nucleoli. The cytological differential diagnoses of these tumours overlap; thus, the cytological findings of the different entities included in their differential diagnoses are discussed.

A Huge Plantar Intramuscular Hemangioma in the Plantar Area Treated Surgically: A Case Report and Literature Review

Intramuscular hemangioma (IH) is rare, accounting for only 0.8% of all hemangioma cases. In particular, IH of the foot has only been reported a few times. In such cases, the symptoms typically include tenderness and swelling, often in relation to physical activity, but tingling or impaired function may also be present. Here, we report a patient who presented with a significant IH in the plantar area treated surgically. A 25-year-old female visited our hospital with pain in the plantar aspect of the right foot. She had noticed a mass about 10 years prior. She had previously experienced pain only when pressing the mass, but the pain subsequently became more regular pain and was exacerbated by exercise. In fact, the pain became so intense that she could not sleep well. Upon physical examination, mild swelling and tenderness of the plantar area were noted in the second to the fourth metatarsal. Sensation and motor reflexes were normal and the results of Tinel’s test were negative. Plain radiographs of the right foot revealed phleboliths scattered throughout the first to third intermetatarsal spaces. Magnetic resonance imaging revealed a space-occupying multilobulated mass (5.6 × 2.8 × 2.5 cm) located in the flexor digitorum brevis (FDB) muscle, which penetrated the plantar fascia and spread to the subcutaneous layer. In T2-weighted images, the lesion displayed a hyperintense signal compared to the surrounding skeletal muscle. Based on radiological findings, we suspected IH. The mass surrounded by the FDB muscle was exposed and completely removed via wide excision. IH consisting of cavernous-like vascular structures was diagnosed on pathology. At 1-year follow-up, the patient was almost asymptomatic and had recovered almost full range of motion in the plantar area. Histological analysis and surgery are recommended to remove intramuscular hemangiomas in the plantar area, but if the patient is not suitable for surgery, sclerotherapy or combination treatment should also be considered.

Adult rhabdomyoma presenting as thyroid nodule on fine-needle aspiration in patient with Birt-Hogg-Dubé syndrome: Case report and literature review

Extracardiac rhabdomyoma is an uncommon benign striated muscle tumor with a predilection for the head and neck region. However, it is extremely rare for extracardiac rhabdomyoma to present as a thyroid nodule. We report a case of rhabdomyoma diagnosed by thyroid fine-needle aspiration (FNA) in a patient with Birt-Hogg-Dubé (BHD) syndrome. A 60-year-old man with BHD syndrome presented for recurrent pneumothorax. Chest CT incidentally identified a thyroid nodule. Subsequent sonography confirmed a 4.44 × 2.28 × 2.82 cm solid, hypoechoic nodule with smooth margins in the right upper pole. Ultrasound-guided FNA revealed many clusters and scattered isolated large polygonal cells with abundant granular cytoplasm and small peripherally located nuclei. Vague striations in the cytoplasm were focally identified. No follicular cells or colloid was present. Immunocytochemistry on one direct smear slide demonstrated diffuse positivity for desmin, supporting muscular differentiation. Subsequent surgery identified an adult rhabdomyoma originating from the inferior constrictor muscle of the neck and anteriorly displacing the thyroid. Because the mass was intimately associated with the thyroid gland, it was initially mistaken for a thyroid nodule on ultrasound. Diagnosis of rhabdomyoma on FNA is challenging, especially when rhabdomyoma mimics a thyroid nodule on imaging. The differential diagnosis includes Hurthle cell neoplasm, granular cell tumor, colloid nodule, and normal striated skeletal muscle. Adequate radiologic data and familiarity with the cytologic features of rhabdomyoma are critical for an accurate diagnosis.

Clinical and Cytogenetic Profiles of Rhabdomyosarcoma with Bone Marrow Involvement in Korean Children: A 15-Year Single-Institution Experience

Background

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in children. Alveolar RMS (ARMS) is characterized by FOXO1-related chromosomal translocations that result in a poorer clinical outcome compared with embryonal RMS (ERMS). Because the chromosomal features of RMS have not been comprehensively defined, we analyzed the clinical and laboratory data of childhood RMS patients and determined the clinical significance of chromosomal abnormalities in the bone marrow.

Methods

Fifty-one Korean patients with RMS <18 years of age treated between 2001 and 2015 were enrolled in this study. Clinical factors, bone marrow and cytogenetic results, and overall survival (OS) were analyzed.

Results

In total, 36 patients (70.6%) had ERMS and 15 (29.4%) had ARMS; 80% of the ARMS patients had stage IV disease. The incidences of bone and bone marrow metastases were 21.6% and 19.6%, respectively, and these results were higher than previously reported results. Of the 40 patients who underwent bone marrow cytogenetic investigation, five patients had chromosomal abnormalities associated with the 13q14 rearrangement. Patients with a chromosomal abnormality (15 vs 61 months, P=0.037) and bone marrow involvement (17 vs 61 months, P=0.033) had a significantly shorter median OS than those without such characteristics. Two novel rearrangements associated with the 13q14 locus were detected. One patient with concomitant MYCN amplification and PAX3/FOXO1 fusion showed an aggressive clinical course.

Conclusions

A comprehensive approach involving conventional cytogenetics and FOXO1 FISH of the bone marrow is needed to assess high-risk ARMS patients and identify novel cytogenetic findings.

Infiltrating angiolipoma of the foot: magnetic resonance imaging features and review of the literature

Angiolipoma is a benign soft tissue tumor with two subtypes: non-infiltrating and infiltrating. Although histologically benign, infiltrating angiolipoma can invade surrounding structures. The foot is a very rare location for angiolipoma, with only four cases reported in the English literature, including one infiltrating type. Here, we report a very rare case of infiltrating angiolipoma of the foot with magnetic resonance imaging (MRI) and ultrasonography (US) findings. A 7-year-old boy presented with a slowly growing foot mass. MRI showed an unencapsulated mass involving the third web space extending to the foot dorsum and sole. The mass was isointense to subcutaneous fat and was mixed with internal T1 low-signal-intensity enhancing areas. On US, we observed a heterogeneously hypoechoic mass with internal vascularity. Imaging and clinical features of angiolipoma and the radiologic differential diagnoses of a fat-containing mass in the pediatric foot are reviewed here. When there is an ill-defined foot mass with a fat component and variable enhancing portions in a child, infiltrating angiolipoma should be included in the differential diagnosis along with other fat-containing tumors.

MR Imaging of Atraumatic Muscle Disorders

Atraumatic disorders of skeletal muscles include congenital variants; inherited myopathies; acquired inflammatory, infectious, or ischemic disorders; neoplastic diseases; and conditions leading to muscle atrophy. These have overlapping appearances at magnetic resonance (MR) imaging and are challenging for the radiologist to differentiate. The authors organize muscle disorders into four MR imaging patterns: (a) abnormal anatomy with normal signal intensity, (b) edema/inflammation, (c) mass, and (d) atrophy, highlighting each of their key clinical and imaging findings. Anatomic muscle variants, while common, do not produce signal intensity alterations and therefore are easily overlooked. Muscle edema is the most common pattern but is nonspecific, with a broad differential diagnosis. Autoimmune, paraneoplastic, and drug-induced myositis tend to be symmetric, whereas infection, radiation-induced injury, and myonecrosis are focal asymmetric processes. Architectural distortion in the setting of muscle edema suggests one of these latter processes. Intramuscular masses include primary neoplasms, metastases, and several benign masslike lesions that simulate malignancy. Some lesions, such as lipomas, low-flow vascular malformations, fibromatoses, and subacute hematomas, are distinctive, but many intramuscular masses ultimately require a biopsy for definitive diagnosis. Atrophy is the irreversible end result of any muscle disease of sufficient severity and is the dominant finding in disorders such as the muscular dystrophies, denervation myopathy, and sarcopenia. This imaging-based classification, in correlation with clinical and laboratory data, will aid the radiologist in interpreting MR imaging findings in patients with atraumatic muscle disorders. ^©RSNA, 2018.

Intramuscular Haemangioma of the Extensor Pollicis Brevis Muscle with Periosteal Reaction of the Radius: A Case Report and Review of the Literature

We report the rare case of a histologically proven mixed-type intramuscular haemangioma, adjacent to the periosteum of the radius, that caused a periosteal reaction. We also carried out a review of the literature relevant to this case. A 28-year-old male professional drummer presented with an 8-month history of pain and swelling of the dorsal aspect of the right radius. Diagnosis was established on the basis of plain radiographs and magnetic resonance imaging, and was confirmed by histology. The lesion was treated solely by resection of the soft-tissue mass. The patient remained asymptomatic 4 years post-operatively, with no radiographic signs of recurrence. From a review of the literature, it is evident that the terminology for haemangiomas causing regional bone changes is unclear. A new classification of the intramuscular haemangiomas is proposed in order to distinguish between lesions that, according to current knowledge, exhibit radiological and clinical areas of overlap.

Pleomorphic rhabdomyosarcoma of the cerebellopontine angle in an adult: a review of literature

Rhabdomyosarcoma (RMS) is a rare and aggressive neoplasm characterised by rapid growth and metastatic invasion. The most frequent localisation is the skeletal musculature of the limbs. The head and the neck are rarely involved. A 50-year-old woman presented to our attention because of a progressively increasing headache, ataxia and vomiting. MRI showed a lesion at the right cerebellopontine angle. Thereafter, the patient was submitted to a piece-meal removal of the neoplasm. Despite the postoperative MRI showed no signs of remnant, 7 months after the surgery, the disease recurred with multiple localisations, and the patient died a few days later. This report is the first description in the literature of a pleomorphic RMS of the cerebellopontine angle. This particular tumour carries a bad prognosis because of the vicinity of nervous structures and of the impossibility of achieving a one-piece resection. More than ever, the adjunctive treatments had to be effective against a potential remnant and in controlling recurrences.

Incidence trends and long-term survival analysis of sinonasal rhabdomyosarcoma

PURPOSE

Sinonasal rhabdomyosarcoma (SNRMS) is a rare malignancy which often presents with nasal obstruction, rhinorrhea and epistaxis. It is the most common sarcoma in children. In this study, we analyze the incidence and long-term survival for SNRMS using a national population-based database.

METHODS

The United States National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry was utilized to calculate incidence and survival trends for SNRMS between 1973 and 2009. In addition, data were grouped by age, gender, race, and histopathological subtype.

RESULTS

A total of 181 cases of SNRMS were analyzed for incidence trends, showing a 1.23:1 female to male ratio. While the overall incidence of SNRMS increased by 1.02% annually over the last 20years, this pattern was not equal amongst gender and racial groups. The incidence in males has increased, while in females incidence has decreased. An increase in incidence was noted in white and "others," but decreased in blacks. Using a total of 314 cases for survival analysis, we found that the rate in the white population has been consistently highest with a 5-year survival of 49.45%, 10- and 20-year survival of 48.81%. Survival rates in cases of embryonal SNRMS were also consistently higher than in cases of alveolar SNRMS.

CONCLUSION

Overall incidence of SNRMS is increasing. Histologic subtype and race are important considerations in the long-term prognosis of SNRMS. Future studies will further elucidate gender and race related trends.

Recurrent adult-type rhabdomyoma: a rare differential diagnosis of "swellings in the masticatory muscle"

Rhabdomyomas are rare benign mesenchymal tumors with skeletal muscle differentiation and a predilection for the head and neck area. A 38-year-old man presented with persistent, slowly growing, painless swelling in the left inner cheek for 2½ years. The lesion was detected during routine dental examination and was considered to represent a mucocele. The mass was removed via a transoral surgical approach, followed by a local recurrence 6 months later that was again surgically removed. The patient is alive and well 2 months after last surgery. Adult-type rhabdomyoma is a rare, occasionally recurring, benign mesenchymal tumor that should be included in the differential diagnosis of submucosal swellings in the oral cavity including the masticatory musculature. Adult-type rhabdomyoma of the cheek and masticatory area are exceptionally rare with no more than 3 cases reported to date.

Paranasal sinus rhabdomyosarcoma: a rare tumor of poor prognosis

INTRODUCTION

Rhabdomyosarcoma (RMS) is a rare sarcoma, in which paranasal sinus locations are exceptional in adults.

CASE REPORT

We report a case of ethmoid metastatic RMS in a 48-year-old patient, discovered in connection with recurrent epistaxis associated with exophthalmia and ophthalmoplegia. The tumor was inoperable and chemotherapy based on adriamycin was initiated. The course was, however, marked by rapid worsening of symptoms and the patient's death.

DISCUSSION

Paranasal sinus RMS shows no specific clinical signs, and diagnosis is mainly based on immunohistochemical analysis. The association of surgery and chemo-radiotherapy is the optimal attitude, but surgical resection is often impossible due to local extension. Prognosis in adults is poor.

Epididymis rhabdomyoma: a case report and literature review

Genital rhabdomyoma is very rare tumor that usually occurs in the vulvar of young women. Epididymis rhabdomyoma in a young man is extremely uncommon and has rarely been reported. Here, we report a case of epididymis rhabdomyoma of a 17-year-old man and review the literatures.

Adult rhabdomyoma in the parapharyngeal space: report of 2 cases and review of the literature

Rhabdomyomas are rare benign mesenchymal tumors with skeletal muscle differentiation. They are less commonly encountered than are their malignant counterparts, rhabdomyosarcomas. Rhabdomyomas fall into 2 general categories: cardiac and extracardiac types. Extracardiac rhabdomyomas are among the rarest tumors in humans and can be subclassified as fetal, juvenile, and adult types depending on the individual tumor's degree of differentiation by light microscopy. Adult extracardiac rhabdomyoma has a strong predilection for occurrence in the head and neck, mainly in the area of larynx and pharynx. In this article, 2 cases of parapharyngeal rhabdomyoma are reported together with a review of the world literature.

Intramuscular hemangioma of the foot: A case report and review of the literature

Intramuscular hemangiomas (IHs) are rare benign neoplasms usually seen in children, adolescents and young adults. Although lower extremities are the commonest localization, the localization at the foot is extremely rare since only a few cases have been reported. We report a case of mixed type IH of the flexor digitorum brevis muscle in a 12-year-old boy who was treated with surgical excision, with wide surgical margins.

Angiolipoma in head and neck: report of two cases and review of the literature

Angiolipomas are either encapsulated or non-encapsulated fatty tumours. They are distinguished from other lipomas by the excessive degree of vascular proliferation and because they are mixed with mature adipocytes. They commonly occur in the trunk and extremities and are rare in the maxillofacial area. Only 36 cases in the head and neck have been reported in the literature. The authors report the first non-infiltrating intramasseterine angiolipoma, and a case of non-infiltrating angiolipoma of the cheek. These tumours appear as homogenous low-density areas on CT with no contrast enhancement. MRI gives better tumour delineation and clear definition of the location and longitudinal extent of the mass. Histopathology demonstrates mature adipose tissue and the proliferation of numerous small branching blood vessels. Management of angiolipomas requires complete surgical excision.

Intramuscular hemangioma: recurrence risk related to surgical margins

The best treatment for intramuscular hemangiomas is unclear in part because the outcome is variable, with recurrence rates ranging from 18% to 61%. This variance is due to deficiencies in previous reports such as an inadequate population size, lack of life table analyses, lack of uniform pathologic criteria, and loose or absent definition of surgical margins. Our goal was to address these deficiencies and support or refute previous results. We identified 110 patients between 1981 and 2005. There were 48 males and 62 females with an average age of 22 years at the time of consult. Kaplan-Meier analysis showed 76% of patients managed initially without excision were surgery-free at 2 years and 66% at 5 years. For patients treated with surgery, 86% and 73% were recurrence free at 2 and 5 years, respectively. There were substantial differences in local recurrence when stratified by margin: 93% of patients were recurrence free at 5 years when the excision was marginal and wide, 65% when intralesional without any gross remaining tumor, and 33% when intralesional with gross remaining tumor. Surgical margins and tumor size were the only identified risk factors for recurrence.

Rhabdomyosarcomas in adults and children: an update

CONTEXT

Rhabdomyosarcomas comprise a relatively common diagnostic entity among childhood cancers and a relatively rare one among adult tumors. They may possess a variety of histologies that generally differ among age groups. These lesions appear to be separate biologic entities as well as morphologic categories, with embryonal tumors having genetic lesions related to loss of heterozygosity and aberrant parental imprinting, alveolar tumors containing genetic fusions between PAX and forkhead genes, and pleomorphic tumors showing an accumulation of genetic lesions similar to other adult high-grade sarcomas.

OBJECTIVE

To present guidelines for diagnosis of rhabdomyosarcoma and recent finding concerning the biology and classification of these lesions.

DATA SOURCES

Review of recent and older published literature and distillation of the authors' experience.

CONCLUSIONS

Infants and young children tend to have embryonal rhabdomyosarcomas, adolescents and young adults tend to have alveolar rhabdomyosarcomas, and older adults tend to have pleomorphic rhabdomyosarcomas, although there is some overlap. Newer rare entities, including spindle cell rhabdomyosarcoma and sclerosing rhabdomyosarcoma, have been described in children and adults. Fusion-positive tumors have a distinct molecular signature with downstream activation of a number of myogenic and tumorigenic factors. Genetic testing may be successfully used for diagnosis and may guide therapy in future clinical trials. Differential diagnosis has become simpler than in previous years, because of use of myogenic factors in immunohistochemistry, but classification based solely on histologic features remains challenging.

Long-term follow-up and prognosis of orbital apex syndrome resulting from nasopharyngeal rhabdomyosarcoma

PURPOSE

Nasopharyngeal rhabdomyosarcoma may present with a variety of ophthalmic symptoms. Direct extension of the tumor into the orbital apex can lead to ophthalmoplegia and loss of vision. The prognosis for recovery of vision and ocular motility in patients with an orbital apex syndrome due to nasopharyngeal rhabdomyosarcoma is examined.

DESIGN

Retrospective case series.

METHODS

Six eyes from four patients with nasopharyngeal rhabdomyosarcoma who presented to the Children';s Hospital of Philadelphia with a clinical orbital apex syndrome were identified. Complete ophthalmic examination, including visual acuity and extraocular motility at the time of presentation, was reviewed. Tumor extension into the orbital apex was confirmed radiographically. Follow-up ophthalmic evaluations were reviewed for all patients with an average follow-up of 5.5 +/- 3.1 years (range 1 to 8 years).

RESULTS

Six eyes of four patients had limited ocular ductions along with marked loss of vision at presentation. All patients were treated with chemotherapy and radiation, with reduction of tumor mass. Ocular motility recovered in all patients, occurring by an average of 2.2 +/- 1.8 months after initiation of therapy. Four of six eyes had little or no recovery of visual acuity detected at long-term follow-up.

CONCLUSIONS

Patients with ocular motor deficits in orbital apex syndromes caused by extension of nasopharyngeal rhabdomyosarcoma have an excellent prognosis for recovery after treatment of the tumor. The long-term prognosis for visual recovery, however, is poor.

Adult paravertebral pleomorphic rhabdomyosarcoma infiltrating diffusely the whole spinal axis

✓ The authors report a unique case of diffuse spinal metastatic disease due to a pleomorphic rhabdomyosarcoma (RMS) in an adult. In additon to its overall rarity, peculiar characteristics of the particular tumor included its site of origin, demonstrated radiologically as the lumbar paravertebral musculature (psoas muscle) and the transcanalicular spread into the vertebral canal, resulting in thecal compression at multiple levels. The salient clinicopathological characteristics of RMS, as they related particularly to the spine, are subsequently discussed and a short review of the major therapeutic modalities for these tumors is offered.

Epididymal rhabdomyoma: report of a case, including histologic and immunohistochemical findings

Genital rhabdomyoma is a rare tumor of skeletal muscle origin that is usually found in the vulvar area of young women. The English literature contains only 2 previous case reports involving men, both of whom were 19 years old. One of these lesions originated in the tunica vaginalis of the testis, and the other originated in the prostate gland. We present the clinical, histologic, and immunohistochemical findings of an epididymal rhabdomyoma in a 20-year-old man. To our knowledge, this is the first such case reported in this location.

Pediatric skin tumors

This article summarizes several malignant childhood neoplasms and benign tumors that can mimic malignancies. Because malignant skin tumors are rare in children, parents and physicians often are not sufficiently suspicious to ensure that an early diagnosis can be made. Many malignant skin tumors have features that suggest a vascular or hemangioma-like lesion. Because hemangiomas occur in 10% of infants, it is often considered prudent to adopt a wait-and-see attitude; however, if the lesion is too firm to be a hemangioma or its growth pattern does not follow that of a typical hemangioma, additional options should be considered. To manage childhood skin malignancies, one needs expert consultation, early biopsy, and correct histopathologic interpretation.

Infiltrating angiolipoma of the M. temporalis

Angiolipomas are rare benign mesenchymal tumours that are distinguished from common lipomas by a marked degree of vascularisation. They are differentiated into non-infiltrating and the even less frequent infiltrating angiolipomas. The present case is the 9th report of an infiltrating angiolipoma of the head and neck. The patient was a 63-year-old man with an infiltrating angiolipoma of the left M. temporalis. Microscopic examination showed univacuolated adipose cells mixed with capillaries invading skeletal muscle. The patient has been free of recurrence since excision of the tumor.

Adult rhabdomyoma: report of two cases of rhabdomyoma of the lip and of the eyelid

We describe two cases of adult rhabdomyoma. One was located in the lip of a 66-year-old woman and was removed because it was clinically suspicious for infiltrating carcinoma. The other arose in the eyelid of a 60-year-old woman with a glass eye and was initially interpreted as a reactive process due to the prosthesis. Both lesions were composed of cells with oval nuclei and deeply eosinophilic cytoplasms with occasional cross striations. Immunoreactivity for desmin and myoglobin excluded the diagnosis of other tumors with similar morphology. The unusual association of the eyelid tumor with the prosthesis suggests a role for chronic irritation in the pathogenesis of rhabdomyoma.

Perianal fetal rhabdomyoma: case report

A 4-week-old female was referred with a firm, enlarging perianal mass present since birth. At surgery, the lesion appeared to be arising from the subcutaneous external sphincter. Local excision was successful with preservation of the external sphincter. Histologic examination showed a mixture of undifferentiated spindle cells as well as immature and maturing myofibers consistent with a fetal rhabdomyoma. This report represents the second case of a fetal rhabdomyoma arising in the perianal location. All pediatric cases of fetal rhabdomyoma in the literature are reviewed.

Microsatellite instability in childhood rhabdomyosarcoma is locus specific and correlates with fractional allelic loss

Replication errors (RERs) were initially identified in hereditary nonpolyposis colon cancer and other tumors of Lynch syndrome II. Mutations in genes involved in mismatch repair give rise to a mutator phenotype, resulting in RERs. The mutator phenotype is thought to predispose to malignant transformation. Here we show that in the embryonal form of childhood rhabdomyosarcoma, RERs also occur, but in contrast to hereditary nonpolyposis colon cancer, only a subset of the microsatellite loci analyzed show RERs. The occurrence of RERs is strongly correlated with increased fractional allelic loss (P < 0.001), suggesting that the occurrence of RERs is a secondary phenomenon in rhabdomyosarcoma. Coincidental loss of genes involved in mismatch repair, possibly due to their proximity to tumor suppressor genes involved in tumor progression of embryonal form of childhood rhabdomyosarcoma, could explain the observed phenomenon.

p53 gene mutation in cerebral primitive neuroectodermal tumor in Taiwan

p53 mutation has been rarely reported in cerebral primitive neuroectodermal tumors (PNET). To determine the significance of p53 mutations in the development of cerebral PNET, we studied cerebral PNET samples from 14 patients, 8 females and 6 males with a mean age of 38 years (range 10 months to 77 years) who had total or subtotal surgical resection. Histological typing of PNET with neuronal (N) and non-neuronal (NN) differentiation groups revealed 8 and 6 cases, respectively. Six (43%) of the 14 patients had p53 mutation. The p53(+) and p53(-) groups had an age range of 19-77 with a mean of 49 years and 10 months to 57 years with a mean of 30 years, respectively. p53 expression between the PNET-N and PNET-NN groups was 5 of 8 (62.5%) and 1 of 6 (16.7%), respectively. The mutations contained 3 transitions, 2 transversions and 1 frameshift; none of them occurred at the site of 'hot-spot' residues (codons 175, 248, 273). The results suggest that: (1) p53 mutation in cerebral PNET tends to show a higher incidence of neuronal differentiation and occurs in the older age group in Taiwan, (2) there was no difference in survival time between the PNET-N and PNET-NN groups (7 months and 6 months) (P = 0.54), and between p53(+) and p53(-) groups (6 months and 7 months) (P = 0.57), and (3) PNET may be an entity of a heterogenous group of tumors with different genetic mechanisms controlling their trends of differential lineage. Further studies are needed to determine the significance of p53 mutations in PNET development, especially the role of carcinogens in the genesis of PNET in Taiwan.

Pleomorphic soft tissue myogenic sarcomas of adulthood. A reappraisal in the mid-1990s

325 diverse sarcomas, 39 rhabdomyosarcomas (RMS), including all histologic variants, and 135 leiomyosarcomas (LMS) were identified. Within these two groups, 18 (46%) of the RMS and 14 (10%) of the LMS represented pleomorphic variants. These neoplasms were studied by morphology (histology and ultrastructure) and by immunohistochemical methods employing antibodies to intermediate filaments (vimentin and desmin) and actin isoforms [alpha-smooth (sm) and alpha-sarcomeric (sr) actins]. Twenty-four pleomorphic malignant fibrous histiocytomas (MFH) and eight pleomorphic liposarcomas (LS) were examined in a similar fashion. By light microscopy, the pleomorphic RMS, LMS, and MFH were indistinguishable, as each was dominated by pleomorphic cells disposed in a haphazard growth pattern; moreover, many featured fascicular, storiform, and sclerotic zones. The distinction between these neoplasms became apparent only following immunohistochemistry and/or ultrastructural study. All pleomorphic RMS disclosed rudimentary sarcomeres and exhibited the following cytoskeletal profile: vimentin (+) (18 of 18), desmin (+) (14 of 18), alpha-sr actin (+) (18 of 18) and alpha-sm actin (+) (five of 18). All the pleomorphic LMS featured smooth-muscle differentiation of variable degrees in the form of cytoplasmic bundles of microfilaments and associated dense bodies; their cytoskeletal profile was vimentin (+) (14 of 14), desmin (+) (seven of 14), alpha-sr actin (+) (none of 14), and alpha-sm actin (+) (eight of 14). The latter was demonstrated in all moderately differentiated, but absent or only focally expressed in poorly differentiated variants. All pleomorphic MFH and LS were devoid of myogenic (skeletal or smooth) ultrastructural features and expressed vimentin solely. This combined morphological and immunohistochemical study illustrates the following: First, these pleomorphic sarcomas are often indistinguishable by histologic growth pattern alone; thus, an accurate diagnosis requires study with all of these techniques. Second, pleomorphic myogenic sarcomas are restricted to adults and are not uncommon neoplasms among pleomorphic sarcomas: RMS (28%), LMS (21%), MFH (38%), and LS (13%). Third, the study defines desmin-negative and alpha-sm actin-positive pleomorphic RMS, and desmin-negative and alpha-sm-actin-negative pleomorphic LMS.

Unilateral hearing loss due to a rhabdomyoma in a six-year-old child

A case report of a six-year-old child is presented, who had had a unilateral sensorineural hearing loss for several years. Because of impairment in the ABR as well as in the caloric testing a MRI and CT scan were performed. A 17 mm tumour in the cerebellopontine angle (CPA) was detected, which after suboccipital surgery proved to be a rhabdomyoma. This tumour has not been described before in the CPA. Unilateral sensorineural hearing loss should, at all ages, be an indication for further (radiodiagnostic) investigations.

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.

Rhabdomyosarcoma mimicking Wilms' tumor

A case of a 6 year old child, with a pleomorphic rhabdomyosarcoma involving simultaneously the leg muscles and the kidney is reported. The renal tumor distorted the pyelocalycial system and Wilms' tumor was the clinical diagnosis. The authors discuss on the possible primary site of the tumor.

Adult intracardiac rhabdomyoma resembling the extracardiac variant

Rhabdomyomas are benign striated muscle neoplasms that may assume a number of characteristic histologic patterns. These lesions may be classified as cardiac or extracardiac on the basis of their location and histology. We present a case of large intracardiac mass with the morphologic features of an extracardiac rhabdomyoma occurring in an adult female.

Differentiation dependent matrix formation (fibronectin and laminin) in an experimental murine rhabdomyosarcoma model

Cellular differentiation processes along with formation of extracellular matrix proteins were investigated in methylcholanthrene-induced murine rhabdomyosarcomata. We used primary tumours, allotransplants in nude mice, and the respective tumour recurrences generated by repeated incomplete surgical tumour removal. The expression of the differentiation markers desmin and myoglobin as well as the presence of fibronectin and laminin was ascertained by immunohistochemical methods. The question arises, whether or not correlations between the grade of cellular differentiation (desmin, myoglobin) and extracellular matrix formation (fibronectin, laminin) exist in tumours with striated muscle cell differentiation. The constant relations between cellular differentiation and matrix formation in original tumours also applied to allotransplants and tumour recurrences in which partially modulations of differentiation in comparison with original tumours could be recognized.

Experimentally induced murine rhabdomyosarcomas--correlation between cellular contacts, matrix formation and cellular differentiation

Rhabdomyosarcomas (RMSs) consist of a mixture of primitive mesenchymal cells as well as cells showing various stages of rhabdomyomatous differentiation. The qualitative and quantitative degree of the rhabdomyomatous differentiation of the cells, evaluated by their morphology and expression of defined structural and functional proteins, is accepted as the basis of diagnosis and is considered to be related to the biological behaviour of RMSs. Therefore we investigated solid experimentally induced murine RMSs, adherent (subconfluent, confluent) cell cultures obtained therefrom, and also suspension cultures and studied the expression of muscular differentiation markers (vimentin, desmin, myoglobin) and the formation of extracellular matrix components (fibronectin, laminin). When we compared solid tumours with adherent cell cultures of decreasing cell densities (confluent up to single cells) and with cells grown in suspension, we found a gradual decline of differentiation ("dedifferentiation"). This decline paralleled the decrease of cell-cell and cell-substrate contacts. In suspension cultures, cells were prevented from interacting with each other and the substratum, no rhabdomyomatous differentiation of the cells took place. If restoration of cellular contacts was allowed, either by adherent growth or by reinoculation into nude mice, the process of dedifferentiation was completely reversible. Consequently, it was demonstrated that the increase of cell-cell and cell-substrate contacts was strongly associated with the appearance or increasing expression of the desmin intermediate filament cytoskeleton and with formation of the extracellular matrix components fibronectin and laminin. The microfilament (F-actin) system was modulated from an impressive stress-fiber system in subconfluent to a dense network in confluent monolayers. The extent of cell-substrate contacts, mediated by extracellular matrix components, and the number of cell-cell interactions are responsible for the capability of a malignant mesenchymal cell, which is able to undergo rhabdomyomatous differentiation, to achieve the various stages of maturation.

Clinical and pathologic features of primary gastric rhabdomyosarcoma

The authors report a case of a collision tumor composed of a primary gastric rhabdomyosarcoma intermingled with an adjacent infiltrating gastric adenocarcinoma. Only eight cases of gastric rhabdomyosarcoma have been reported previously and little information is recorded about the behavior of this tumor. Gastric rhabdomyosarcoma has several distinctive clinical features. It is a highly aggressive tumor (median survival, 2.5 months) occurring in both children and adults and frequently presents as metastatic disease to lung or cervical lymph node. The initial diagnosis is often difficult to establish, especially on biopsy material. In several instances, the correct diagnosis was established only at autopsy. The authors' patient was correctly diagnosed during life and received considerable benefit from cyclophosphamide, doxorubicin, and vincristine (CAV) therapy and survived for 26 months after diagnosis. Two of the previously reported eight cases of primary gastric rhabdomyosarcoma and this case have adjacent admixed glandular gastric adenocarcinomas. Since three of the nine known cases of primary gastric rhabdomyosarcoma have an adjacent admixed gastric adenocarcinoma, there appears to be a greater than chance association between these two tumors.

Intramuscular Haemangioma of the Forearm

Intramuscular haemangioma, though benign, may be a serious disorder, because its large size can cause functional impairment, pain and disfigurement, which may require surgical excision. These, as well as the baffling histopathological aspects, are exemplified by this report of an intramuscular haemangioma of the forearm in an adolescent girl. Clinical recognition of a cutaneous angioma overlying a deeply-situated soft tissue tumour may aid the diagnosis of an intramuscular haemangioma.

Prenatal detection of non-cardiac rhabdomyosarcoma

The most prevalent soft tissue tumour in children is rhabdomyosarcoma. These tumours may develop within or outside of muscle anywhere in the body and at any age. We report what is apparently the earliest case of non-cardiac rhabdomyosarcoma detected prenatally.

Laryngeal botryoid rhabdomyosarcoma in an adult. Report of a case with electron microscopic study

Light and electron microscopic studies of botryoid rhabdomyosarcoma of the larynx in an adult are presented. Differences in cellular composition of the central and peripheral regions of the tumor are described. The ultrastructure of the rhabdomyoblasts is discussed on the basis of criteria recently described. The findings support the hypothesis that botryoid rhabdomyosarcoma is a special subtype of rhabdomyosarcoma with low grade malignancy.

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).

Rhabdomyosarcoma in middle-aged and elderly individuals

In a review of a national series of malignant tumors in middle-aged and elderly individuals (over 40 years of age), in all 107 cases primarily diagnosed and reported to the Swedish Cancer Registry as rhabdomyosarcomas during the period 1972-1981, 4 cases were accepted as botryoid, embryonal or alveolar rhabdomyosarcoma, using light-microscopic criteria for the diagnosis. An electron-microscopic and immunohistochemical analysis was performed on the 4 cases along with 7 cases of botryoid, embryonal and alveolar rhabdomyosarcoma in patients of over 40 years of age obtained from our own files. Rhabdomyoblastic differentiation was established ultrastructurally by the presence of myofilaments and Z-like densities in 10 of these 11 cases. There were tumor cells in the formaldehyde-fixed, paraffin-embedded material which were positively stained for desmin in all cases, for myoglobin in 7/11 cases, for vimentin in 5/11 cases and for actin in all cases, using monoclonal antibodies. The demonstration of desmin by the monoclonal antibody which was used on the formaldehyde-fixed, paraffin-embedded material is of particular value in the diagnosis of rhabdomyosarcoma. Another tumor, located in the minor pelvis, lacked the light-microscopic features of botryoid, embryonal or alveolar rhabdomyosarcoma, but presented ultrastructural and immunohistochemical evidence of a rhabdomyoblastic differentiation. This tumor was epithelioid in appearance and shared features with alveolar soft part sarcoma. The label epithelioid rhabdomyosarcoma is proposed for this tumor. Nine pleomorphic sarcomas were selected from the national series as possible pleomorphic rhabdomyosarcomas because of the presence of ribbon-shaped tumor cells with an eosiniphilic cytoplasm. There was no electron-microscopic or immunohistochemical evidence of a myogenic differentiation in any of these 9 tumors. The present investigation indicates that a pleomorphic type of rhabdomyosarcoma, indistinguishable from embryonal, botryoid and alveolar rhabdomyosarcoma, is extremely rare or non-existent.

Cytokeratin expression in experimental murine rhabdomyosarcomas. Intermediate filament pattern in original tumors, allotransplants, cell culture and re-established tumors from cell culture

Soft tissue sarcomas were induced by 20-methylcholanthrene in NMRI-mice. The tumors were characterized as rhabdomyosarcomas by light and electron microscopy as well as immunohistochemistry (vimentin, desmin and myoglobin expression). Cytokeratins could be demonstrated by a panel of different poly- and monoclonal antibodies in original rhabdomyosarcomas, their allotransplants and the re-established tumors from cell culture in nude mice. The cytokeratin positive tumor cells were arranged in small clusters and/or haphazardly single dispersed in the rhabdomyosarcomas. By means of monoclonal antibodies cytokeratins No. 8 and No. 19 could be evidenced and cytokeratin No. 18 could be made probably. Behind the background of cytokeratin expression in developing fetal cross striated muscle cells our findings are discussed as a reminiscence of embryonal muscle development in these tumors. The significance of cytokeratin expression in rhabdomyosarcomas for diagnostic histopathology is emphasized.