Intrarenal solitary fibrous tumor of the kidney report of a case with emphasis on the differential diagnosis in the wide spectrum of monomorphous spindle cell tumors of the kidney

Solitary fibrous tumor (SFT) is a neoplasm that can occur in the urogenital tract, and is also reported occurring in the spermatic cord, seminal vesicles, urinary bladder, prostate, and kidney. Furthermore, it is most important to consider its existence in the kidney, because it is usually diagnosed as renal cell carcinoma pre-operatively. To our knowledge, only 10 cases of SFT have been reported in the kidney to date. We report the clinico-pathological features of an intrarenal SFT occurring in a 31-year-old woman. The tumor, measuring 8.6 cm in its greatest diameter, completely replaced the cortex and the medulla of the middle region of the right kidney, compressing the pelvis. Radiological imaging was consistent with a renal cell carcinoma. Histologically, the tumor was composed of a proliferation of bland-looking vimentin+, CD34+, bcl2+ and CD99+ spindle cells exhibiting a haphazard to storiform growth pattern, pushing borders, and a low mitotic rate (2 mitoses x 10 HPF). We placed emphasis on the differential diagnostic problems, i.e., its differentiation from other primary monomorphous benign and malignant spindle cell tumors of the kidney, such as fibroma, benign fibrous histiocytoma, hemangiopericytoma, inflammatory myofibroblastic (pseudo-)tumor, leiomyoma, angiomyolipoma with predominant spindle cell smooth muscle component, benign peripheral nerve sheath tumors, renal mixed epithelial/stromal tumors, adult type mesoblastic nephroma, fibrous type monophasic synovial sarcoma, malignant peripheral nerve sheath tumors, fibrosarcoma, and low-grade fibromyxoid sarcoma.     

Intra-abdominal spindle cell lesions: a review and practical aids to diagnosis

Intra-abdominal spindle cell lesions are uncommon and often present a diagnostic challenge. An important group of such lesions are the gastrointestinal stromal tumours. Other intra-abdominal spindle cell lesions include fibromatosis, various sarcomas-in particular, leiomyosarcoma, liposarcoma, and malignant peripheral nerve sheath tumour-and, in women, endometrial stromal sarcoma. Less common lesions are inflammatory myofibroblastic tumours, the mesenteric spindle cell reactive lesions, retroperitoneal fibrosis, and solitary fibrous tumour. A variety of intra-abdominal tumours of nonmesenchymal origin may have a spindle cell/sarcomatoid morphology; these include sarcomatoid carcinoma, malignant melanoma and, in women, sarcomatoid granulosa cell tumour. Finally, metastatic sarcomas from pelvic or extra-abdominal organs need also be considered. A set of practical aids to the diagnosis of intra-abdominal spindle cell lesions is presented to assist pathologists dealing with such lesions, particularly with regards to the consideration of differential diagnoses.     

Paediatric renal tumours: recent developments, new entities and pathological features

Paediatric renal tumours represent a relatively common group of childhood solid neoplasms, in which both diagnosis and treatment are highly dependent on the histopathological findings. In addition to Wilms' tumour (nephroblastoma), a number of specific distinct entities are now reported, including (congenital) mesoblastic nephroma, clear cell sarcoma of the kidney, rhabdoid tumour of the kidney, specific paediatric variants of renal cell carcinoma, and others such as renal primitive neuroectodermal tumour and desmoplastic small round cell tumour. Recent advances in both molecular biological findings and immunohistochemistry allow reliable diagnosis of most of these entities even on the basis of small needle biopsy specimens. This review highlights both the salient features important for the diagnostic pathologist reporting such cases, and areas in which either new classifications or major advances in diagnostic criteria have occurred in recent years.     

The value of electronmicroscopy and immunohistochemistry in the diagnosis of soft tissue sarcomas: a study of 200 cases

Two hundred soft tissue sarcomas, accrued consecutively over a 4-year period, were examined by light and electronmicroscopy and by routine immunohistochemistry. The commonest tumour type was malignant fibrous histiocytoma. Fibrosarcoma, composed only of fibroblasts, was diagnosed in only one case; three others, composed also of myofibroblasts, could be regarded as fibrosarcomas or myofibrosarcomas. Immunohistochemistry was of most value in the diagnosis of rhabdomyosarcoma, leiomyosarcoma, malignant peripheral nerve sheath tumour of Schwann cell type and epithelioid sarcoma. Electronmicroscopy was of most use for the diagnosis of malignant peripheral nerve sheath tumour of perineurial cell type and marker-negative monophasic synovial sarcoma, and for confirming malignant fibrous histiocytoma. Fifteen of 19 marker-negative spindle cell tumours (79%) were diagnosable by electronmicroscopy. A combination of techniques resulted in a specific diagnosis in 193 cases (96.5%). The routine use of electronmicroscopy in sarcoma diagnosis can improve accuracy of diagnosis, establish the true frequency of marker-positivity for each ultrastructurally confirmed tumour type and minimise the number of unclassifiable cases.     

Cellular congenital mesoblastic nephroma in a newborn

Typical nephroblastoma (Wilms'tumor) is uncommon within the first 6 months of life. Renal tumors most commonly found in this age constitute of two groups which have a better and worse prognosis, respectively, than typical nephroblastomas. The group of tumors with a better prognosis encompasses congenital mesoblastic nephroma (CMN), fetal rhabdomyomatous nephroblastoma and cystic, partially differentiated nephroblastoma. The group of tumors with a worse prognosis consists of rhabdoid tumor of the kidney and bone metastasizing renal tumor (clear cell sarcoma) of childhood. Adequate therapy for these two neoplasms has as yet to be developed. Among the low-grade malignant tumors congenital mesoblastic nephroma can be successfully treated with simple nephrectomy. There, are however, variants of CMN which may differ in clinical behavior from the typical form of CMN. These variants include the cellular CMN2 and, possibly, the malignant mesenchymal nephroma of infancy. A case of cellular congenital mesoblastic nephroma is presented here. Its clinical and pathologic features are discussed.     

Benign tumors and tumor-like lesions of the adult kidney. Part II: Benign mesenchymal and mixed neoplasms, and tumor-like lesions

In this review article the benign tumors and tumor-like lesions of the adult kidney are discussed. The incidence of benign renal tumors is low, especially when compared to renal cell carcinomas, as most are detected incidentally or at autopsy. Some of these tumors, as their names imply, are unique to the kidney, e.g., renal adenoma, metanephric adenoma, renal oncocytoma, nephrogenic adenofibroma, mesoblastic nephroma, capsuloma, juxtaglomerular cell tumor, renomedullary interstitial cell tumor (medullary fibroma), cystic nephroma, cystic partially differentiated nephroblastoma, and cystic hamartoma of the renal pelvis, while others, such as angiomyolipoma, leiomyoma, hemangioma, lipoma, etc., are not unique to the kidney and show similar morphologic features in the other sites they affect. Of the tumor-like lesions, xanthogranulomatous pyelonephritis, malakoplakia, and renal cysts are the most common. The other entities, such as fibroepithelial polyp, are rare, most having been the topic of case reports. In Part I of this paper the benign epithelial tumors of the kidney were previously discussed. This paper (Part II) is devoted to the benign mesenchymal tumors, mixed mesenchymal and epithelial tumors, and the tumor-like lesions.     

Study of childhood renal tumours using antisera to fibronectin, laminin, and epithelial membrane antigen.

Using a peroxidase-antiperoxidase staining procedure, formalin fixed paraffin embedded sections of fetal and normal kidney; benign (mesoblastic nephroma); and malignant tumours (Wilms' tumour, clear cell renal carcinoma, rhabdoid renal tumour, and bone metastasising renal tumour of childhood (BMRTC] were examined for their reactivity with antisera to fibronectin, laminin, and epithelial membrane antigen. Mesoblastic nephroma contained fibronectin but no laminin. Most Wilms' tumours lacked both fibronectin and laminin; 50% of rhabdoid renal tumours were positive for fibronectin and laminin--rhabdoid tumours as recognised morphologically may, in fact, be two separate entities. BMRTC and clear cell renal carcinoma lacked both fibronectin and laminin. Epithelial membrane antigen was present in most of the tubular Wilms' tumour but absent in blastemal Wilms' tumours. The presence of epithelial membrane antigen in rhabdoid tumours was surprising, as histologically, this type of tumour shows no sign of epithelial differentiation. Epithelial membrane antigen antiserum stained clear cell renal carcinomas: epithelial membrane antigen is found in the distal and not the proximal tubules of fetal and normal kidneys. Thus an obvious interpretation is that clear cell renal carcinomas originate from distal rather than from proximal tubules, as has always been thought. On the basis of these results and data from other published findings some possible histogenetic origins of childhood renal tumours were proposed.     

Primary renal tumours in the first year of life

Summary Of 30 patients presenting with primary renal tumours in the first year of life, there were 23 Wilms' tumours (15 classical, six epithelial and two rhabdomyomatous), three rhabdoid neoplasms and four mesoblastic nephromas. Criteria for the diagnosis of rhabdoid tumours and mesoblastic nephromas are discussed with reference to histological difficulties. Although Wilms' tumour was the commonest neoplasm, mesoblastic nephroma predominated in the first three months of life. The clinical behaviour of the cases is reviewed, and rhabdoid tumours, although relatively few in number, accounted for a significant part of the overall mortality.Consultant Pathologist to the Royal Manchester Children's Hospital. Honorary Lecturer in Pathology, University of ManchesterSenior Lecturer in Pathology and Honorary Consultant Pathologist     

Dendritic cell sarcomas/tumours of the breast: report of two cases

Extranodal follicular dendritic cell sarcoma/tumours (FDCS/Ts) and interdigitating dendritic cell sarcoma/tumours (IDCS/Ts) are rare neoplasms. We present two cases of FDCS/T and IDCS/T of the breast. The FDCS/T case (case 1) presented in a 31-year-old woman and the IDCS/T case (case 2) in a 67-year-old woman who both showed a firm lump in the left breast. The FDCS/T lesion superficially appeared as an anaplastic carcinoma and the IDCS/T was reminiscent of a spindle cell sarcomatoid carcinoma. Nevertheless both lesions were negative for keratins while case 1 displayed neoplastic cells strongly positive for CD21, vimentin and focally for CD68 and S-100 protein. The tumour cells of case 2 were positive for S-100, CD68 and CD45. In breast, an unusual keratin negative tumour composed predominantly of spindle cells arranged in fascicles, storiform pattern or whorls with a lymphoid rich stroma should raise suspicion for FDCS/Ts or IDCS/Ts. The distinction from malignant tumours with similar features is discussed.     

Spindle cell tumours of the breast: practical approach to diagnosis

Spindle cell tumours of the breast are uncommon and often present diagnostic challenges. The most important is the sarcomatoid/metaplastic carcinoma, which has monophasic and biphasic variants. Each of these groups presents special diagnostic difficulties. In the monophasic variant the mesenchymal component predominates and the epithelial element forms a minor component often detected only after immunohistochemical study. The spindle cell areas may be bland and therefore under-diagnosed as nodular fasciitis or fibromatosis. Alternatively they may be highly malignant with a pattern that is misinterpreted as primary sarcoma of the breast. In the biphasic variant, the difficulty is in distinguishing between sarcomatoid carcinoma, myoepithelial carcinoma or malignant phyllodes tumour. Other spindle cell lesions of the breast include the various myofibroblastic tumours, the spindle cell variant of adenomyoepithelioma, the varied primary breast sarcomas, metastatic tumours with spindle cell morphology and, finally, the very rare follicular dendritic cell tumour. A simple practical approach to the diagnosis of spindle cell lesions is presented to help the general surgical pathologist to compile a differential diagnosis and to arrive at the correct conclusion     

Cellular mesoblastic nephroma in an infant: Report of the cytologic diagnosis of a rare paediatric renal tumor

Congenital mesoblastic nephroma is a rare pediatric tumor with a favorable clinical outcome. Cytological features of this uncommon tumor and diagnostic difficulties with other commoner pediatric renal neoplasms have been inadequately discussed in the available literature. We describe the case of a 1‐year‐old girl who presented with a right renal mass. Fine‐needle aspiration smears consisted of a few cellular clusters of spindle cells with mitotic activity and mild nuclear pleomorphism. No blastema was identified. A cytologic impression of mesoblastic nephroma was rendered, which was confirmed on histopathological examination of the right nephrectomy specimen as a cellular mesoblastic nephroma. Cytologic diagnosis of mesoblastic nephroma has important prognostic and therapeutic implications. The cytopathologist should carefully evaluate smears from such patients and attempt to differentiate mesoblastic nephroma from Wilms' tumor and clear cell sarcoma. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.     

Lessons learned from the developmental origins of childhood renal cancer

Despite the rarity of renal tumors in children, many different types of malignant and nonmalignant renal neoplasms have been described. Therefore, the correct diagnosis and clinical management of these patients can represent a challenge. Here we provide a comprehensive review of the commonly diagnosed pediatric renal malignancies, including nephroblastoma (commonly known as Wilms tumor), clear cell sarcoma of the kidney, rhabdoid tumor of the kidney, several subtypes of renal cell tumors (often collectively termed renal cell carcinoma), and congenital mesoblastic nephroma. The epidemiology, pathology, treatments, underlying genetic and molecular mechanisms, and proposed developmental origins are discussed in detail, highlighting differential features and potential improved therapeutic strategies for affected individuals.     

Spindle cell lesions of the adult prostate.

Prostatic spindle cell lesions are diagnostically challenging and encompass a broad array of benign and malignant processes. A subset of these lesions arises only within the prostate and generally represents entities that originate from the prostate epithelium or stroma, such as sclerosing adenosis, sarcomatoid carcinoma, stromal tumors of uncertain malignant potential (STUMP), and stromal sarcoma. Another subset of spindle cell tumors that involve the prostate are also found at other sites and include solitary fibrous tumor, leiomyosarcoma, and neural lesions among others. Finally, tumors may secondarily involve the prostate yet present as primary prostatic processes, as is evident with several cases of gastrointestinal stromal tumors (GIST). The utility of ancillary studies, including immunohistochemistry, is often limited and the main criteria for diagnosis are the morphologic findings by routine H&E stain. This review addresses the various entities that may present as spindle cell tumors within the adult prostate and discusses the functional aspects of the differential diagnosis of these lesions.     

Anti-mesothelial markers in sarcomatoid mesothelioma and other spindle cell neoplasms

AIMS: To undertake a comparative evaluation of three antimesothelial markers (thrombomodulin, cytokeratin 5/6 and calretinin) with broad spectrum cytokeratin (AE1/AE3) in differentiating between sarcomatoid mesothelioma and a spectrum of spindle cell neoplasms. METHODS AND RESULTS: Thirty-one malignant sarcomatoid mesotheliomas were studied. Calretinin expression was focally identified in 12 (39%) tumours and thrombomodulin and cytokeratin 5/6 immunoreactivity was seen in nine (29%) cases. In comparison there was strong diffuse cytoplasmic reactivity with the broad spectrum cytokeratin (AE1/AE3) in 24 of 31 (77%) tumours. Thirty mixed spindle cells neoplasms were studied. No calretinin expression was identified in any case. Thrombomodulin immunoreactivity was identified in four (16%) cases (two angiosarcomas, two high-grade sarcomas, not otherwise specified). Cytokeratin 5/6 expression was seen in one high-grade pulmonary sarcoma originally termed malignant fibrous histiocytoma. None of the antimesothelial markers was expressed in the four spindle cell carcinomas studied. In contrast, broad spectrum cytokeratin was diffusely expressed in all four spindle cell carcinomas (three pulmonary, one renal), both synovial sarcomas, both malignant mixed Müllerian tumours, one of three pulmonary leiomyosarcomas and two of nine sarcomas, not otherwise specified. CONCLUSIONS: Immunohistochemistry has a more limited role in the diagnosis and distinction of sarcomatoid mesothelioma from other spindle cell neoplasms. The combination of a broad spectrum cytokeratin with calretinin combines both high sensitivity (77% for AE1/AE3) with high specificity (100% for calretinin) for sarcomatoid mesothelioma and can be diagnostically useful. The mesothelial markers, thrombomodulin and cytokeratin 5/6, are not useful alone in the diagnosis of sarcomatoid mesothelioma as each shows insufficient antibody sensitivity, although together they complement calretinin.     

Spindle cell tumors of the pleura: differential diagnosis

Spindle cell tumors that arise in or metastasize to the pleura must be thoroughly evaluated to arrive at a definitive diagnosis. Malignant mesothelioma is the most common tumor arising in the pleura, but metastatic tumors to the pleura occur more frequently. Additionally, many tumors arising in the lung and surrounding tissues involve the pleura. It is crucial to arrive at a correct diagnosis since many of these neoplasms show different prognoses and require varying treatment modalities. Sarcomatoid malignant mesothelioma is a rare tumor that arises in the pleura, and can be confused with numerous tumors arising in or metastasizing to the pleura, including synovial sarcoma, metastatic sarcomatoid carcinoma, metastatic melanoma, thymoma, renal cell carcinoma, localized fibrous tumor, leiomyosarcoma, and other types of sarcoma. Desmoplastic malignant mesothelioma is a fibrous sarcomatoid variant of malignant mesothelioma, and is occasionally mistaken for chronic fibrous pleurisy. Here, we review morphological, clinical, histological, immunohistochemical, ultrastructural, and molecular methods that aid in the diagnosis of spindle cell tumors of the pleura, and we provide specific examples of patients in which this multi-modal approach proved to be helpful.     

Caecal adenocarcinoma with rhabdoid phenotype: An immunohistochemical and ultrastructural analysis

Summary A polypoid caecal adenocarcinoma in a 72-year-old female was found microscopically to be composed mainly of rhabdoid cells. Deposits in the liver and lymph nodes had a similar histological appearance to the primary tumour. The rhabdoid cells were typified by abundant eosinophilic cytoplasm, eccentric nuclei and prominent nucleoli. The differential diagnosis included rhabdomyosarcoma, metaplastic carcinoma (carcinoma with sarcomatoid dedifferentiation), carcinosarcoma and extra-renal rhabdoid tumour. The rhabdoid cells showed strong immunoreactivity with cytokeratin, epithelial membrane antigen and vimentin. Ultrastructurally, cytoplasmic whorls of intermediate filaments were noted. Multiple sections, immunohistochemistry and ultrastructural examination all revealed an adenocarcinomatous component which blended with the rhabdoid areas. In one area a rhabdoid cell was present within a malignant gland. This case illustrates that the rhabdoid appearance of many tumours can be misleading and is merely a non-specific morpho-phenotypic pattern seen in extra-renal sites. In the extra-renal setting, careful search for evidence of differentiation should be undertaken.     

Analysis by comparative genomic hybridization of epithelial and spindle cell components in sarcomatoid carcinoma and carcinosarcoma: histogenetic aspects.

Sarcomatoid carcinomas and carcinosarcomas are histologically malignant biphasic neoplasms with an epithelial and a spindle cell component. Both a polyclonal and a monoclonal origin have been postulated for these tumours, but the latter has been favoured. For carcinosarcoma, the stem cell from which the epithelial and mesenchymal components are derived is expected to be more immature than the epithelial stem cell from which different components of sarcomatoid carcinoma originate, since in the latter, immunohistochemical or ultrastructural epithelial characteristics are still detectable. In the present study, comparative genomic hybridization was used to test the hypothesis that both tumour components in sarcomatoid carcinoma have more chromosomal aberrations in common than those in carcinosarcoma. From three sarcomatoid carcinomas originating from the urinary bladder and two carcinosarcomas from the pharynx, the epithelial and spindle cell components were microdissected and analysed for their respective chromosomal aberrations, using comparative genomic hybridization. High-level homology was seen in chromosomal aberrations between the different components in each tumour. This level of homology was even higher in the carcinosarcomas (65 and 91 per cent) than in both sarcomatoid carcinomas (21-51 per cent). The different phenotypic components of both sarcomatoid carcinoma and carcinosarcoma show a large overlap of chromosomal aberrations, strongly suggesting a monoclonal origin for all of these tumours. These findings do not support the hypothesis that the divergence between epithelial and spindle cell components occurs at an earlier stage in carcinosarcomas than in sarcomatoid carcinoma.     

乳腺肉瘤样癌

观察乳腺肉瘤样癌的病理形态学特点,分型,并分析其与某些肿瘤的鉴别诊断。方法１５３８例乳腺恶性肿瘤中１５例（０．９８％）诊断为乳腺肉瘤样癌,行ＡＥ１／ＡＥ３、上皮膜抗原（ＥＭＡ）、波形蛋白、Ｓ－１００蛋白、肌动蛋白、雌激素受体（ＥＲ）和孕激素受体（ＰＲ）ＳＰ法免疫组织化学染色。另有６例是外院会诊病例,共２１例。结果按其肉瘤样成分的特点分为４个形态学类型：（１）多形肉瘤型：肉瘤样成分为多形肉瘤样。（２     

Monosomy 22 in a malignant peripheral nerve sheath tumour of the kidney in childhood: a genetic link with other malignant paediatric renal neoplasms?

A recurrent malignant spindle cell neoplasm of the kidney, occurring in a 11-year-old girl and corresponding to a malignant peripheral nerve sheath tumour is reported. The neurogenic differentiation was substantiated by the presence of PGP 9.5 neurofilament and S-100 protein positivity and by the ultrastructural features. Cytogenetic analysis revealed monosomy of chromosome 22 in the tumour while the constitutional karyotype was normal. Primary malignant peripheral nerve sheath tumour of the kidney is extremely rare and should, on morphology, be differentiated from stromal predominant Wilms' tumour and clear cell sarcoma of the kidney. Involvement of chromosome 22 has been described in a number of malignant renal tumours of childhood, such as Wilms' tumour (deletion), clear cell sarcoma (translocation), and rhabdoid tumour (deletion and translocation), thus suggesting common molecular mechanisms in pediatric malignant renal tumours.