Gangliorhabdomyosarcoma: a histopathological and immunohistochemical study of three cases

More Than Meets the Eye? A Cautionary Tale of Malignant Ectomesenchymoma Treated as Low-risk Orbital Rhabdomyosarcoma

Malignant ectomesenchymoma (MEM) is a rare multiphenotypic tumor comprised of mesenchymal and neuroectodermal components. MEM is typically diagnosed in infants and younger children and outcomes are variable. The current approach for treating MEM includes targeting the more aggressive mesenchymal component of the tumor, which is often rhabdomyosarcoma. Here, we describe a case of an orbital tumor initially diagnosed and treated as low-risk rhabdomyosarcoma. Local failure prompting a second biopsy revealed neuronal differentiation consistent with a diagnosis of MEM. Intensifying therapy and local radiotherapy led to a long-term cure. This case offers a cautionary tale that while outcomes for MEM were similar to matched rhabdomyosarcoma cohorts when treated on conventional Intergroup Rhabdomyosarcoma Study Group (IRSG) III/IV protocols, treating MEM using a decreased intensity low-risk rhabdomyosarcoma regimen may not be sufficient.

An Adult Paratesticular Malignant Ectomesenchymoma With Post-operative Flare-up of Lung Metastasis

Malignant ectomesenchymoma (MEM) which is derived from the remnants of migratory neural crest cells (ectomesenchyme) is a rare and rapidly progressing tumor consisting of neuroectodermal and mesenchymal neoplastic elements. This tumor occurs mostly in children and adolescents, but rarely in adults. We report a 34-year-old male with left paratesticular malignant ectomesenchymoma who received radical orchiectomy and was followed by post-operative flare-up of lung metastasis within 2 weeks. We present the overall treatment strategies for this extremely rare tumor and related findings.

Malignant ectomesenchymoma in children and adolescents: report from the Cooperative Weichteilsarkom Studiengruppe (CWS)

BACKGROUND

Malignant ectomesenchymoma (MEM) is a soft tissue tumor with heterologous rhabdomyoblastic components believed to arise from pluripotent migratory neural crest cells. To date merely 50 cases have been published and the knowledge about the course of disease and optimal treatment is limited.

METHODS

Six patients with MEM were registered 1996-2009. The diagnosis was confirmed according to current criteria. Their treatment and outcome was analyzed.

RESULTS

The median age of the three females and three males was 0.6 years (range, 0.2-13.5). The mesenchymal component in all tumors was rhabdomyosarcoma (RMS), the neural component ganglioneuroblastoma/neuroblastoma (n = 5) and peripheral primitive neuroectodermal tumor in one case. Five patients presented with localized, one with metastatic disease. All but one patient received multiagent chemotherapy during their initial treatment. The tumors of 4/5 patients with localized MEM were at least grossly resected at best surgery; the patient without gross resection was additionally irradiated. Three of four evaluable tumors responded well to induction chemotherapy. All patients achieved a first complete remission (CR), but three recurrences (two local, one systemic) occurred. The individual with metastatic MEM did not survive, but all five patients with localized MEM are currently alive in CR with a median follow-up of 5 years (range: 2.1-13.7).

CONCLUSIONS

Risk-factors and outcome of MEM appear to be comparable with other highly malignant pediatric soft tissue sarcoma when a multimodal treatment strategy including chemotherapy and adequate local treatment is pursued. We propose that treatment of patients with MEM be done according to pediatric protocols similar to other rhabdomyosarcoma-like soft tissue sarcoma.

Nonepithelial Tumors and Tumor-Like Lesions of the Prostate Gland

Many significant benign and malignant nonepithelial tumors and stromal tumor-like lesions arise in the prostate gland. Although such lesions are rare, their recognition by the pathologist is essential because their treatment and prognosis are quite variable. In this review, lesions of the specialized prostatic stroma, that is, lesions that can be seen in the stroma of the prostate but not in that of other organs, except for the phyllodes type of lesions, are discussed. Benign and malignant lesions of the soft tissues that occur in the stroma of other organs and are seen with some frequency in the prostate are also discussed. Few of the rarer soft tissue lesions are mentioned. Lesions and tumors with melanocytic differentiation, hematopoietic derivation, and germ cell tumors are described. It is hoped that this review will serve as a useful reference when encountering some of these lesions, all of which are referenced to their original and subsequent reports. Some non-English language references are also cited to reflect the international recognition of these lesions or to give credit to the author who first described the entity.

Primitive small cell tumor with epithelial, gangliocytic, neuroendocrine, and mesenchymal differentiation: report of 2 cases

The authors describe 2 tumors that, to the best of their knowledge, are hitherto undescribed. The predominant cell type was small round to fusiform dark blue cells. The dark blue cells formed distinct epithelial cords with gland-like formations with mucicarmine-positive mucus. Another distinctive component of the tumors was a mesenchymal one. The mesenchymal areas appeared benign and could be likened to a fibroma having a densely collagenous stroma, or they had spindle cells set in the myxoid background, rendering a myxoma-like appearance. Another distinctive feature was ganglion cell differentiation. Mitotic figures, including atypical forms, were found only in the small cell component. All cells were immunohistochemically negative for actin, calponin, desmin, HMB45, neurofilament protein, CD99/MIC2, Melan A, tyrosinase, serotonin, CD56, Melan A, GFAP, and S-100 protein. Cytokeratin, synaptophysin, FLI1 protein, and chromogranin antibodies reacted only in the primitive small round cells, while all the other components were cytokeratin negative. Fluorescence in situ hybridization showed that the tumors are without the EWSR1 gene translocation and gain 12p. Ultrastructurally, the cells were endowed with well-formed intercellular desmosomes membrane-bound secretory in the cytoplasm. Granules were found in the cytoplasm. We suggest the name "primitive small cell tumor with epithelial, gangliocytic, neuroendocrine, and mesenchymal differentiation" for this neoplasm.

Molecular array analyses of 51 pediatric tumors shows overlap between malignant intracranial ectomesenchymoma and MPNST but not medulloblastoma or atypical teratoid rhabdoid tumor

Gene microarray has been used to identify prognostic markers and genes of interest for therapeutic targets; a less common use is to show possible histogenetic relationships between rare tumor types and more common neoplasms. Intracranial malignant ectomesenchymoma (MEM) is a pediatric tumor postulated to arise from neural crest cells that contain divergent neuroectodermal and mesenchymal tissues, principally mature ganglion cells and rhabdomyosarcoma (RMS). We investigated a case of MEM by molecular, cytogenetic, and gene array analyses and compared results with our previously unpublished series of 51 pediatric tumors including conventional RMS, Ewing sarcoma (EWS), medulloblastoma (MED), atypical teratoid rhabdoid tumor (ATRT), and malignant peripheral nerve sheath tumor (MPNST); the latter is a sarcoma also with potential for divergent differentiation. Standard cytogenetic analyses and RT-PCR testing for the classic gene rearrangements seen in RMS [t(2;13)-PAX3/FKHR] and EWS ([t(11;22) & t(21;22)-EWS/FLI-1 & EWS/ERG), were used for characterization of the MEM, with gene expression microarray analyses on all tumor types. Gene rearrangement studies were negative in MEM. Gene expression microarray analyses showed tight clustering of the MEM with the MPNST (n = 2), but divergence from other pediatric tumors. MEM and MPNST both showed complex karyotypes, but without diagnostic translocations. Despite the presence of malignant skeletal muscle differentiation in the MEM, gene array testing showed no overlap with RMS, MED, or ATRT, but rather with MPNST. This suggests a common stem cell origin or embryonic gene recapitulation for these tumors and provides novel insights into their underlying biology.

Malignant ectomesenchymoma in the wrist of a child: case report and review of the literature

Malignant ectomesenchymomas, rare and potentially aggressive tumors, occur in children and exhibit mesenchymal and neuroectodermal components. This report describes the first patient diagnosed with a malignant ectomesenchymoma of the hand. The patient was a 17-month-old male who developed a hypothenar mass on his left hand that was surgically excised. Microscopic evaluation revealed ganglioneuroblastic, rhabdomyosarcomatous, and chondrosarcomatous elements. Following excisional biopsy he was treated with cyclophosphamide, doxorubicin, vincristine, ifosfamide, and etoposide. After 3 courses of chemotherapy the patient had a wide reexcision with no residual tumor. The patient is 4 years from diagnosis, without evidence of disease.

Clinicopathologic study of ectomesenchymomas from Intergroup Rhabdomyosarcoma Study Groups III and IV

Ectomesenchymomas (EM) are rare malignant neoplasms usually consisting of rhabdomyosarcoma (RMS) with a neural component. Only 21 cases have been previously reported. Here we extend the clinicopathologic spectrum of EM by describing our findings in 15 cases. Only 5 patients were infants; 10 were < or =3 years old and 5 were > or =6 years old. No male predilection was observed; 7 were female. The originating institutional diagnoses were; RMS (12), undifferentiated sarcoma (1), or EM (2), suggesting underdiagnosis of this entity. The primary tumor sites included external genital (5), pelvis/abdomen (6), head and neck (3), and extremity (1). The size of the primary neoplasm was usually > or =5 cm at diagnosis but dissemination only occurred in a minority. Local infiltration was not uncommon. These neoplasms were typically multilobate, thinly encapsulated, hemorrhagic, and necrotic. Light microscopic features were highly variable, but embryonal RMS with scattered or clustered ganglion cells, often in lacunae, was characteristic. In some cases, primitive neuroblastic or neuroectodermal areas were found and/or a component of alveolar RMS was seen. Focal anaplasia was occasionally observed. Mitotic activity appears higher than previously appreciated and some necrosis was invariably present. Electron microscopy was performed in 11 cases, which confirmed skeletal muscle +/- neural differentiation. Cytogenetic studies performed in five cases revealed no specific abnormality. Monoclonal neuron-specific enolase was the best marker of ganglion cells and primitive neural elements. MIC-2 (CD99) membrane expression was not definitively present in any of the six cases examined. A number of the above parameters appear to be of some prognostic significance, but overall, these neoplasms appear to have a similar outcome as would be predicted for their RMS element alone (exclusive of any neural component), with respect to the RMS subtype, age of the patient, and anatomic location of the neoplasm.

Rhabdomyosarcoma metastasizing as a malignant ectomesenchymoma

Rhabdomyosarcoma is a common childhood malignancy that may occasionally occur as a component of a mixed mesenchymal tumor, e.g., a triton tumor or malignant ectomesenchymoma. A case is reported of a 13-year-old boy who had resection of a paratesticular embryonal rhabdomyosarcoma with subsequent radiation and chemotherapy. Two years later, a retroperitoneal metastasis was resected. Histology showed a mixture of rhabdomyoblasts, ganglion cells, and a third population of cells with combined features of these two distinct cell types. Electron microscopy confirmed the presence of rhabdomyoblasts with characteristic bundles of myofilaments and Z-band material, and ganglion cells with prominent nuclei and nucleoli, rough endoplasmic reticulum, dense core granules, filaments, and tubules. Notably, the third cell population showed features of both rhabdomyoblasts and ganglion cells. Immunohistochemistry confirmed the mixed population of rhabdomyoblasts (positive for vimentin, desmin, negative for S-100, NSE), ganglion cells (positive for S-100 and NSE, negative for vimentin and desmin), and the third population expressing all test antigens. The features of this metastatic lesion are those of a malignant ectomesenchymoma with combined rhabdomyosarcoma and ganglioneuroma components. It is postulated that this lesion results from biphenotypic expression of tumor cells that previously expressed only rhabdomyoblastic differentiation. The role of prior chemotherapy and radiotherapy in this particular case is unclear.

Spindle cell sarcoma of the kidney with ganglionic elements (malignant ectomesenchymoma) associated with chromosomal abnormalities and a review of the literature

PURPOSE

Malignant ectomesenchymomas are tumors that exhibit both mesenchymal and neuroectodermal elements (1). We report a case thought to represent a malignant ectomesenchymoma arising in the kidney with cytogenetic abnormalities that may provide insight into the biologic basis for this unusual tumor.

METHODS

We discuss the clinical features, histopathologic findings, cytogenetics, treatment, and outcome of a child with a malignant ectomesenchymoma arising in the kidney.

RESULTS

An asymptomatic 16-month-old boy had a large abdominal mass. The resected tumor contained sheets of spindled cells that expressed mesenchymal markers and cartilaginous differentiation, interspersed with clusters of ganglion cells that expressed neural markers. No blastemal or epithelial elements were demonstrated. Cytogenetic analysis of the tumor revealed a hyperdiploid count with multiple numerical and structural abnormalities, including a translocation between chromosomes 12 and 15. In addition to the surgical resection, the patient was successfully treated with adjuvant chemotherapy and local radiation therapy.

CONCLUSION

This is the first report of which we are aware of an ectomesenchymoma arising within the kidney. A subset of malignant ectomesenchymomas may be related to the Ewing's family of tumors (EFTs) (2), but this case did not exhibit cytogenetic features consistent with EFT. Thus, the malignant ectomesenchymoma phenotype probably represents a heterogeneous group of tumors with different genotypes and origins. Cytogenetic analysis may be instrumental in determining the appropriate therapeutic approach when faced with such a neoplasm. The outcomes of 12 other children with ectomesenchymoma are reviewed.

Primary neuroblastoma presenting as a paratesticular tumor

A 3-month-old boy was operated on for an inguinal tumor. Histological diagnosis was neuroblastoma. This is the second known case of primary paratesticular neuroblastoma reported in the literature. The treatment of choice for Evan's stage I is surgery.

Ectomesenchymal hamartoma (benign "ectomesenchymoma") of the VIIIth nerve: case report

We report a previously undescribed hamartoma of the VIIIth nerve, consisting of adipose tissue, Schwann cells associated with myelinated nerve fibers, well-differentiated smooth and striated muscle fibers, and rare ganglion cells. The tumor was found in a 35-year-old Caucasian female who presented with right-sided hearing loss. The mass, which we designate an "ectomesenchymal" hamartoma, most likely developed from pluripotent neural crest cells ("ectomesenchyme"), which are capable of differentiating into a variety of neuroectodermal and mesenchymal cell types. The development of the neural crest, the concept of "ectomesenchyme," and the histogenesis of this tumor are reviewed.

Molecular biological aspects of soft tissue tumors

In the preceding, the reader has hopefully developed an appreciation of the major malignant tumors to be encountered in somatic soft tissues in children, adolescents, and young adults. In aggregate, this group of tumors accounts for about 20% of cancer in this age group. Importantly, they are curable tumors when nonmetastatic at presentation, but therapy appropriate to prognosis and tumor responsiveness is highly dependent on precise diagnosis. The historical morphologic methods alone will not suffice for this purpose, but the anticipated rapid advent of molecular genetic diagnostic and prognostic methods should. Useful, practical, and rapid genetic tests, available in the same time frame as the routine histopathologic evaluation of these tumors, are likely to forever change the diagnosis and management of these tumors, individually and as a group.

Primary intracranial sarcomas: histopathological features of 19 cases

Nineteen primary intracranial sarcomas out of a total of about 25,000 brain tumour biopsies are reported. Subtypes included malignant fibrous histiocytoma (6 cases), leiomyosarcoma (3), rhabdomyosarcoma (2), angiosarcoma (2), and one case each of fibrosarcoma, low-grade fibromyxoid sarcoma, malignant ectomesenchymoma, mesenchymal chondrosarcoma, differentiated chondrosarcoma and Ewing's sarcoma. Histological and immunohistochemical features corresponded to those of extracranial sarcomas. Nests of pleomorphic astrocytes mimicking glioma were detected in the five storiform-pleomorphic malignant fibrous histiocytomas. Our results indicate that intracranial sarcomas can be classified like their extracranial counterparts. The low incidence compared with earlier series is related to changes in classification and progress in histogenetic clarification.

Malignant ectomesenchymoma of soft tissue. Report of two cases and review of the literature

The clinical and pathologic findings of two patients with malignant ectomesenchymomas of soft tissue are reported. Malignant ectomesenchymomas are a composite of ganglion cells or neuroblasts and one or more malignant mesenchymal elements, usually rhabdomyosarcoma. Our first case was composed of ganglioneurosarcoma plus rhabdomyosarcoma, the second composed of neuroblastoma plus rhabdomyosarcoma. The name is derived from the suggestion that they arise from pluripotential ectomesenchyme. An English language literature search revealed 11 other cases that arose in soft tissue and had adequate clinicopathologic data. Of the 13 cases, 10 occurred in infants, three occurred in adults, and nine were males. Six patients were alive and free of disease at last follow-up (range, 0.6-12 years; mean, 3.4 years), four patients had died of tumor (within 0.5-3.3 years; mean, 1.3 years), one case had died of Adriamycin (doxorubicin) toxicity, and two cases had been lost to follow-up. Complete surgical resection is the mainstay of treatment and chemotherapy appears to be important.