Extra-adrenal retroperitoneal paraganglioma in a dog.

An extra-adrenal retroperitoneal paraganglioma was observed in a 10.5-year-old male Boxer dog. Additionally, the dog had an aortic base tumor, multiple thyroid adenomas, multiple testicular interstitial cell tumors, bilateral nodular adrenal cortical hyperplasia, and parathyroid gland hyperplasia. The hypothesis that the retroperitoneal mass represents a primary extra-adrenal paraganglioma rather than metastatic mass from the aortic body tumor is considered. Either primary or metastatic extra-adrenal retroperitoneal paragangliomas are rarely reported in dogs.

Diffusion-weighted imaging of retroperitoneal malignant peripheral nerve sheath tumor in a patient with neurofibromatosis type 1.

We present the diffusion-weighted imaging (DWI) findings for a malignant peripheral nerve sheath tumor arising in a retroperitoneal plexiform neurofibroma in a patient with neurofibromatosis type 1. Signal intensity of the malignant area was high on DWI and low on the apparent diffusion coefficient map and differed from findings for the benign area. DWI enabled clear differentiation between malignant and benign areas of the tumor.

Neurilemoma retroperitoneal / Retroperitoneal neurilemmona

El schwanoma es un tumor poco frecuente, que tiene su origen en las envueltas neurales de los nervios periféricos. Para su diagnóstico es fundamental el hallazgo histológico de zonas Antoni A y B. Presentamos un nuevo caso de localización retroperitoneal, que no es su situación más frecuente, en un varón de 60 años, que presentó dolor en flanco izquierdo. Recibió tratamiento quirúrgico, siguiendo una evolución favorable

Schwannoma is an uncommon tumor arising from neural sheath of peripheral nerves. Histological findings showing Antoni A and B zones are the main diagnostic features. ;;We report a new case of a retroperitoneal located one, which is not its most usual place to appear, in a 60 years old male, presenting left flank pain. He recieved surgical treatment, having a satisfactory evolution

Unusual aspects of desmoplastic small round cell tumor.

Desmoplastic small round cell tumor (DSRCT) is a neoplasia that occurs mainly in childhood and involves abdominal or peritoneal sites, coexpressing ectodermal and mesenchimal immunophenotypic markers, and is endowed with an impressive stromal desmoplasia that tends to decrease on tumor relapse. To date, over 150 cases have been collected in the literature. Its presumed neuroectodermal histogenesis has been challenged by cytogenetic findings different from those usually associated with neoplasms of neuroectodermal origin. The authors report a case bearing clinical and histologic aspects of typical desmoplastic retroperitoneal small cell tumor, with intense and diffuse nuclear immunopositivity for WT1, but lacking divergent immunophenotype. Ultrastructural investigation revealed that desmoplasia could result from fibrillary synthesis by neoplastic cells.

Malignant monotypic epithelioid angiomyolipoma of the retroperitoneum.

Monotypic epithelioid angiomyolipoma (EAML) is an uncommon variant of angiomyolipoma, occurring primarily in the kidney and characterized by a predominance of HMB-45-positive epithelioid cells. EAML is generally considered a benign neoplasm, though rare cases exhibiting malignant behavior have been reported. We describe a patient with a primary retroperitoneal monotypic EAML, composed exclusively of atypical epithelioid cells, which metastasized to the liver and the mediastinum. This case represents, to our knowledge, the first description of metastatic disease occurring in an EAML of this particular site.

Evidence of nerve sheath differentiation and high grade morphology in sclerosing epithelioid fibrosarcoma.

Sclerosing epithelioid fibrosarcoma is a recently described sarcoma in which ultrastructural evidence of fibroblastic differentiation forms part of the diagnostic criteria. This report describes a further case of this tumour, which showed evidence of both fibroblastic and perineurial differentiation by immunohistochemistry and electron microscopy, and which had areas of high grade morphology. The tumour metastasised and the patient died of disease 12 months after presentation. The relevance of these findings to diagnosis and differentiation in these tumours is discussed.

Extraovarian granulosa cell tumor.

A 54-year-old woman was admitted to our hospital complaining of postcoital bleeding. Sonography of the abdomen showed a 8.2 x 8.9 cm-sized solid heterogeneous mass occupying the cul-de-sac, which appeared to be in no way connected with the ovary. On exploratory laparotomy, the tumor mass protruded from the posterolateral retroperitoneum of the pelvic cavity and severely replaced the uterus and adnexa with the outer surface being grossly intact. It grossly measured 10 cm in maximal diameter. The histologic features closely resembled those of ovarian granulosa cell tumor. The primary extraovarian granulosa cell tumor is extremely rare such that in the English literature only 7 cases have been reported to date. Of those granulosa cell tumors are especially rare and only two cases have been reported to arise from retroperitoneum. We herein present a case of retroperitoneal granulosa cell tumor with special regard to differential diagnosis from other solid tumors with similar histology.

Extrapleural solitary fibrous tumor: a report of seven cases.

Solitary fibrous tumors (SFTs) are rare, spindle-cell neoplasms generally associated with the serosal surface, especially the pleura. Histopathologic, immunohistochemical, ultrastructural, and flow cytometric analyses were performed on seven SFTs of extrapleural sites (two retroperitoneal, two soft tissue, one each peritoneal, nasal cavity, and orbit). Five patients were women, and two were men, aged from 21 to 68 years (average, 39 yr). All of the lesions presented as well-circumscribed masses. The lesions ranged in size from 2 to 20 cm in greatest diameter. Histologically, these lesions were entirely comparable to the pleural SFTs and lacked the characteristic features of other recognized neoplasms that occur in these regions. One tumor contained pleomorphic and round-cell sarcomatous foci. Immunohistochemically, all of the tumors were strongly positive for vimentin and CD34. Six of the seven tumors showed varying numbers of spindle cells positive for alpha smooth muscle actin, HHF35, neuron-specific enolase, Leu 7, or glial fibrillary acidic protein. Ultrastructural examinations of three tumors showed that they were composed of primitive mesenchymal or fibroblast-like cells. Six tumors examined were diploid by flow cytometric examination. Clinical follow-up in six patients ranged from 1 to 7.5 years (average, 2.6 yr) and showed that five patients remained well with no evidence of disease after excision and that the patient with the sarcomatous elements died of recurrence 2.5 years after surgical treatment. These findings suggest that SFTs represent ubiquitous neoplasms of fibroblasts or primitive mesenchymal cells with aggressive potential.

Progressive approach to the cytologic diagnosis of retroperitoneal spindle cell tumors.

OBJECTIVE: To assess the utility of fine needle aspiration biopsy (FNAB) in retroperitoneal spindle cell tumors with difficult tumor typing. STUDY DESIGN: Thirty-six cases of spindle cell tumors of the retroperitoneum were studied. Cytological diagnoses were set progressively: first exclusively by morphologic criteria on routinely stained slides, and then with the aid of immunocytochemistry (ICC), electron microscopy (EM) and clinical data. RESULTS: The morphologic diagnosis of benignity or malignancy was first made in double blind fashion by two researchers; it permitted an exact diagnosis in 31 cases (86%) by one examiner and 27 cases (75%) by the second. Using a progressive approach, benignity or malignancy was definitively determined in 35 cases (97%). As far as cytologic tumor typing is concerned, first it proved to be possible in 27 cases (75%) and then in 30 cases (83%) with the progressive approach. CONCLUSION: FNAB proved to be a useful tool in the diagnosis of retroperitoneal spindle cell tumors. A progressive approach to cytopathologic diagnosis, correlating morphology with ICC and EM results and matching them with clinical data, permitted a better differential diagnosis between benign and malignant spindle cell tumors and increased the possibility of correct tumor typing.

Image cytometry analysis of Feulgen-stained nuclei in 72 lipomatous lesions including atypical lipomas and well-differentiated liposarcomas.

Well-differentiated lipomatous tumors constitute a histopathologic category whose nomenclature has been controversial, particularly with respect to the distinction between atypical lipomas of the extremities and well-differentiated liposarcomas of the retroperitoneum. To determine whether there were differences in image analytic parameters between these neoplasms, 72 lesions including 21 typical lipomas, 7 atypical lipomas, 16 retroperitoneal and 5 nonretroperitoneal well-differentiated, 9 dedifferentiated, and 14 pleomorphic liposarcomas were submitted to the computer-assisted microscopic analysis of Feulgen-stained nuclei. This methodology enabled four groups of variables to be calculated. These included: (1) quantitative chromatin pattern description (14 variables); (2) the measurement of proliferative activity (1 variable); (3) nuclear DNA content (DNA ploidy level, 5 variables); and (4) the measurement of cell density and topographical cell nuclei organization (2 variables). The results strongly suggest that atypical lipomas, whether superficial or deep, and well-differentiated liposarcomas, whether retroperitoneal or not, belong to the same category in terms of the variables analyzed.

Myxofibrosarcoma. Clinicopathologic analysis of 75 cases with emphasis on the low-grade variant.

Myxofibrosarcoma is one of the most common sarcomas in the extremities of elderly patients. We analysed the clinicopathologic features in a series of 75 patients. All patients were adults (range, 22-91 years; median, 66 years) with an approximately equal incidence in men and women. Thirty-five tumors arose in the lower and 25 in the upper extremities, nine on the trunk, two each in the retroperitoneum and the head and neck region, and one each in the pelvis and penis. Forty-eight cases (69.5%) were located in dermal or subcutaneous tissues. Distinctive histologic features included the following: a commonly nodular growth pattern; a myxoid matrix containing elongated, curvilinear capillaries; and fusiform, round or stellate tumor cells with indistinct cell margins, slightly eosinophilic cytoplasm, and hyperchromatic atypical nuclei. These lesions varied from a hypocellular, mainly myxoid, and purely spindle-cell appearance (low-grade neoplasms) to high-grade, pleomorphic (malignant fibrous histiocytoma-like) lesions with multinucleated giant cells, high mitotic activity, and areas of necrosis. Immunohistochemistry in 44 cases revealed only vimentin and occasional actin positivity. Ultrastructurally, tumor cells had a fibroblastic phenotype. DNA flow cytometry and proliferation analysis showed an association between aneuploidy and histologic grade. An average follow-up of 45 months (range, 5-300 months) in 60 cases has revealed local recurrence in 33 cases (54%). Thirteen patients developed metastases, and 13 tumor-related deaths occurred. A short interval to first local recurrence was associated with poor clinical outcome. The rate of local recurrence was independent of histologic grade, but only intermediate and high-grade neoplasms metastasized. The depth of the primary lesion did not influence the incidence of local recurrence. However, in deep-seated neoplasms, the incidence of metastases was higher and the percentage of tumor-related deaths was twice as high as in superficially located lesions, reflecting the fact that deep-seated lesions tended to be higher-grade, larger tumors. Myxofibrosarcoma tends to become progressively higher grade in recurrences, as demonstrated in five cases in our series. The poorly recognized low-grade myxofibrosarcoma is emphasized, as proper diagnosis and treatment and scrupulous follow-up are mandatory to avoid local recurrence and gradual tumor progression to a higher-grade neoplasm that may then metastasize.

Retroperitoneal malignant meningioma. A light microscopic, immunohistochemical, and ultrastructural study.

Malignant meningiomas are uncommon and rarely occur outside the central nervous system. We describe herein a morphologically unusual malignant neoplasm that arose in the retroperitoneum of a 25-year-old woman. The tumor was composed of sheets of epithelioid cells that were frequently arranged in prominent whorls. By electron microscopy, the neoplastic cells had long, tapering cell processes that formed numerous interdigitations; many junctions including desmosomes; and abundant intermediate filaments. Immunohistochemistry showed that the tumor cells expressed vimentin, keratin, and epithelial membrane antigen. Based on these findings, the neoplasm was classified as a malignant meningioma. According to our review of the literature, this is the first reported occurrence of a primary retroperitoneal meningothelial neoplasm and the second reported case of an ectopic meningioma that was malignant.

Extrarenal Wilms' tumor: an ultrastructural and immunoelectron microscopic case report.

Wilms' tumor is the most common malignancy of the genitourinary tract in children but the occurrence of extrarenal Wilms' tumor is extremely rare. Extrarenal Wilms' tumor, which by definition excludes a primary tumor in the kidney, has been reported less than fifty times. The ultrastructural appearance of renal Wilms' tumor has been well documented, but the present report is believed to be the first description of the ultrastructural appearance of extrarenal Wilms' tumor. The authors report, for the first time, localization of intermediate filament proteins (vimentin and cytokeratin) and epithelial membrane antigen (EMA) by immunoelectron microscopy in this neoplasm. Demonstration of the coexpression of vimentin and cytokeratin within the same blastemal cell, as well as the identification of desmosomes in a cell with vimentin intermediate filaments, suggests a relationship between stroma, blastema, and epithelia similar to that proposed in renal Wilms' tumor.

Mesenchymal chondrosarcoma of the retroperitoneum. Report of a case diagnosed by fine needle aspiration biopsy with immunohistochemical, electron microscopic demonstration of S-100 protein in undifferentiated cells.

BACKGROUND: Mesenchymal chondrosarcoma (MC), first described in 1959 by Lichtenstein and Bernstein, is an uncommon tumor of the soft tissues and bone defined by the coexistence of nests of well-defined cartilaginous tissue within a proliferation of primitive mesenchymal cells. CASE: A 27-year-old, white female consulted a physician for a left lumbar mass associated with sciatica-type pain, asthenia, anorexia and weight loss. Abdominal computed tomography showed a 20-cm, retroperitoneal neoplasm that occupied the lower half of the left abdominal flank. Fine needle aspiration biopsy showed clusters of small round cells mixed with islets of mature cartilage. Immunomarking for electron microscopy, carried out with 15 nm of A protein/colloidal gold, showed specific immunoreactivity to S-100 protein in the nuclear chromatin, nucleoli, Golgi apparatus, plasma membrane and cytosol of cells with more developed organelles. CONCLUSION: The diagnosis of MC rests on recognition of the biphasic component of small, undifferentiated cells and cartilage islets. In aspirates with only undifferentiated cells, demonstration of ultrastructure-specific immunoreactivity to S-100 protein may contribute to the final diagnosis.