Frequent activation of AKT2 and induction of apoptosis by inhibition of phosphoinositide-3-OH kinase/Akt pathway in human ovarian cancer

We previously demonstrated that AKT2, a member of protein kinase B family, is activated by a number of growth factors via Ras and PI 3-kinase signaling pathways. Here, we report the frequent activation of AKT2 in human primary ovarian cancer and induction of apoptosis by inhibition of phosphoinositide-3-OH kinase (PI 3-kinase)/Akt pathway. In vitro AKT2 kinase assay analyses in 91 ovarian cancer specimens revealed elevated levels of AKT2 activity (>3-fold) in 33 cases (36.3%). The majority of tumors displaying activated AKT2 were high grade and stages III and IV. Immunostaining and Western blot analyses using a phospho-ser-473 Akt antibody that detects the activated form of AKT2 (AKT2 phosphorylated at serine-474) confirmed the frequent activation of AKT2 in ovarian cancer specimens. Phosphorylated AKT2 in tumor specimens localized to the cell membrane and cytoplasm but not the nucleus. To address the mechanism of AKT2 activation, we measured in vitro PI 3-kinase activity in 43 ovarian cancer specimens, including the 33 cases displaying elevated AKT2 activation. High levels of PI 3-kinase activity were observed in 20 cases, 15 of which also exhibited AKT2 activation. The remaining five cases displayed elevated AKT1 activation. Among the cases with elevated AKT2, but not PI 3-kinase activity (18 cases), three showed down-regulation of PTEN protein expression. Inhibition of PI 3-kinase/AKT2 by wortmannin or LY294002 induces apoptosis in ovarian cancer cells exhibiting activation of the PI 3-kinase/AKT2 pathway. These findings demonstrate for the first time that activation of AKT2 is a common occurrence in human ovarian cancer and that PI 3-kinase/Akt pathway may be an important target for ovarian cancer intervention.

Expression of beta2 integrins and macrophage-associated antigens in meningeal tumours

This study assessed the expression of leukocyte integrins and macrophage-associated antigens in meningiomas. Fourteen benign meningiomas, ten atypical/anaplastic meningiomas, two hemangiopericytomas and one solitary fibrous tumour (SFT) were included. Frozen sections were immunostained using antibodies directed against leukocyte integrins, CD68, CD14, CD2, CD1a, DRC1 and CD34. Their expression was evaluated semi-quantitatively. Ki67 positive cells were counted. Arachnoid membranes served as controls. Arachnoid cells expressed the beta2-integrin subunit and KP1. Beta2 was detected in the tumour cells of 14 meningiomas. In nine cases, this was associated with an alpha-integrin subunit. There was no statistical difference in the expression of beta2 between benign and atypical/anaplastic meningiomas. KP1 was constantly expressed by the tumour cells of meningiomas. It was not expressed by other meningeal tumours. CD34 was detected in the fibrous meningiomas, hemangiopericytomas and the SFT. In each tumour, macrophages were more numerous than T lymphocytes. There was no statistical difference in the density of macrophages and T lymphocytes between the benign and atypical/anaplastic meningiomas. There was no correlation between the Ki67 proliferation index and macrophage infiltration. Meningiomas, through the expression of leukocyte antigens, have a very particular phenotype. The expression of beta2 integrins could play a role in the attraction of immunocompetent cells in the stroma of meningiomas.

Solitary fibrous tumor of the orbit: a poorly-recognized orbital lesion

PURPOSE

The authors report three cases with solitary fibrous tumor (SFT) of the orbit with variable clinical presentation.

METHODS

The authors identified three patients with a diagnosis of SFT, and clinical histories, radiographs and pathologic specimens were reviewed.

RESULTS

Two SFTs are reported arising in the lacrimal gland fossa of a 24-year-old male and a 26-year-old female and a retrobulbar SFT is reported occurring in a 40-year-old female. While two patients had slow growth histories, one patient had a history of rapid progression. Immunohistochemically, the tumor cells were strongly positive for CD34 in all three cases.

CONCLUSION

The clinical presentation of the orbital SFT may be varied. Immunohistochemical analysis may help in the diagnosis of solitary fibrous tumor and the treatment is en bloc excision. A careful follow-up is necessary because it may recur years after excision of the primary tumor.

Recurrent sclerotic fibroma of the skin

The pathologic findings of a sclerotic fibroma of the skin may resemble those of other benign cutaneous lesions. In this report, the sequential pathologic changes of a recurrent sclerotic fibroma of the skin during a period of 7 years are documented. As the lesion became older, there was not only a decrease in cellularity, but also a progressive organization of the collagen bundles toward a "plywood-like" appearance.

Intraluminal fibromyxoid lesions in bronchiolitis obliterans organizing pneumonia are highly capillarized

Bronchiolitis obliterans organizing pneumonia (BOOP) and usual interstitial pneumonia (UIP; ie, cryptogenic fibrosing alveolitis of mural type, CFA) are clinically and histologically distinguishable interstitial lung diseases. Both contain intraluminal lesions of newly formed fibromyxoid connective tissue. In BOOP, the fibromyxoid lesions are susceptible to complete reversal, but in UIP they are supposed to participate in the remodeling of the interstitium. Our hypothesis was that capillarization of the intraluminal fibromyxoid lesions is more frequent in BOOP compared with UIP. In this study, we stained diagnostic thoracoscopic or open lung biopsy specimens of patients with BOOP (n = 9) and UIP (n = 10) with antibodies against human laminin, von Willebrand factor, and CD34 to reveal the microvasculature of intraluminal fibromyxoid lesions. Our results show that in BOOP there is abundant capillarization in the newly formed intraluminal fibromyxoid lesions often reminiscent of granulation tissue. The mean number of capillaries per area unit (mm2) was 107 +/- SD 74 in samples stained for laminin, 103 +/- SD 46 for von Willebrand factor, and 63 +/- SD 36 for CD34. In marked contrast, in UIP, the corresponding accounts were significantly lower, being 14 +/- SD 15 for laminin (P < .003), 11 +/- SD 14 for von Willebrand factor (P < .001) and 6 +/- SD 6 for CD34 (P < .001). The intraobserver (P < .001) and interobserver correlations (P < .002) were highly significant, showing that our results are reproducible. We conclude that the content and nature of the newly formed intraluminal connective tissue, for example, in the form of vascular growth factors, are different in BOOP and in UIP, and this partly leads to the different clinical course of these diseases.

Differential expression of CD34 and Ki-M1p in pleomorphic fibroma and dermatofibroma with monster cells

Pleomorphic fibroma (PF) and dermatofibroma with monster cells (DFMC) are characterized by the presence of numerous cells with large atypical nuclei. Despite cytologic similarities, the two entities are likely to be unrelated, but their histogenesis is poorly understood. In this study, we examined six cases of PF and eleven cases of DFMC by immunohistochemistry using antibodies against vimentin, alpha-smooth muscle actin, S-100 protein, CD34, factor XIIIa, and the pan-monocytic marker Ki-M1p. Strong vimentin expression was seen in all tumors, whereas none of them expressed S-100 protein. PF consistently exhibited CD34 staining but appeared to be depleted of Ki-M1p positive cells compared with the surrounding normal skin. Conversely, all cases of DFMC contained numerous Ki-M1p positive cells including atypical multinucleate cells, but virtually no CD34 reactivity was observed. A weak staining for alpha-smooth muscle actin was occasionally seen in a subset of the cells of both entities. Our results indicate that PF and DFMC are histogenetically distinct entities that may arise from two different types of dermal dendritic cells defined by their reactivity for CD34 and Ki-M1p, respectively. Immunohistochemistry using these two antibodies permits an easy and reliable discrimination between PF and DFMC.

Cortical benign fibromatous tumor (fibroma) of the kidney

Benign fibromatous tumor (BFT), also named 'fibroma', is a distinctive clinico-pathologic entity occurring in epididymis, spermatic cord, paratesticular structures, testis, renal peripelvis and rarely in renal parenchyma. We report the first case of a BFT (fibroma) located in the cortex of the kidney, and a critical review on the topic is provided. Tumor was found incidentally at autopsy as a small cortical nodule. With the increasing use of radiological imaging of the abdomen, it is likely that an increased number of incidental and asymptomatic benign renal tumors will be diagnosed. We underline that BFT (fibroma) should be considered in the preoperative differential diagnosis of renal cortical nodules.

Giant cell fibroblastoma: an entity or a reactive phenomenon?

The histological and immunohistochemical features of four tumors displaying the characteristic pattern of Giant Cell Fibroblastoma (GCF) are presented. Three of them were found in association with classical and/or myxoid dermatofibrosarcoma protuberans, while the fourth tumor was a retroperitoneal malignant hemangiopericytoma where foci with features of GCF were found. Typical sinusoidal spaces and the bizarre mononuclear and multinucleated cells in close association to blood vessels presenting a wide spectrum of lesions of their walls are also described. These last changes led us to believe that GCF-like lesions might not always characterize an entity but could often represent a host reaction of the connective tissue to locally aggressive or malignant tumors.

Pacinian collagenoma

An unusual histological variant of collagenoma is described. A 36-year-old woman presented with a lump in the left hypothenar eminence. Histological examination revealed a well-delineated lesion composed of paucicellular collagen fibres arranged in concentric lamellations giving rise to an onion skin appearance. The overlying epidermis was thin and the lateral borders were demarcated by an epidermal collarette. Inflammation and xanthoma cells were absent and occasional capillaries were present. The lesion was positive for collagen stains, reticulin and CD34. This lesion represents an uncommon histological form of collagenoma or fibroma. It can be distinguished from histological look-alikes on the basis of the characteristic morphology and immunophenotype.

Desmoplastic fibroblastoma (collagenous fibroma)

Desmoplastic fibroblastoma is a vary rare subcutaneous proliferation. We describe a case of desmoplastic fibroblastoma in a 24-year-old Korean woman who presented with a 2.5 cm solitary and firm nodule on her back which had been present for 3 months. Histologic studies showed a well demarcated subcutaneous tumor composed of stellate or spindle shaped cells embedded in hypovascular fibrous or fibromyxoid stroma. No mitotic figures, calcification, or necrosis were observed. The stellate or spindle shaped cells were positive for vimentin. The stroma stained positively with Alcian blue and Masson trichrome. S-100 protein, actin, desmin, and elastic fiber stains were all negative in the stellate or spindle shaped cells. There has been no recurrence or metastasis of the tumor over an 18-month follow-up.

Collagenous fibroma (desmoplastic fibroblastoma): genetic link with fibroma of tendon sheath?

We observed clonal chromosome abnormalities in two fibrous soft tissue tumors diagnosed as collagenous fibroma (desmoplastic fibroblastoma). The involvement of the same band of the long arm of chromosome 11, 11q12, was observed in both tumors. The presence of hitherto unreported similar chromosomal abnormalities in this tumor supports the neoplastic nature of this lesion. In addition, a possible relationship with fibroma of tendon sheath, which also shows rearrangement of 11q12, is suggested. 11q12 might be a common genetic denominator of benign fibroblastic lesions, such as collagenous fibroma and fibroma of tendon sheath.

Oral lichen planus: an immunohistochemical study of heat shock proteins (HSPs) and cytokeratins (CKs) and a unifying hypothesis of pathogenesis

The expression of heat shock proteins HSP60 and HSP70 and cytokeratins CK1/10 and CK7/18 were compared in epithelium of oral lichen planus (OLP) lesions and oral fibromas using an avidin-biotin-peroxidase complex (ABC) immunohistochemical method. An immunostaining intensity distribution (IID) index was developed to assess staining intensity and the proportion of positively stained cells in different layers of the epithelium. The expression of HSP60 in the basal layer was significantly higher in OLP than in fibromas. No difference in HSP70 expression was evident between OLP and fibromas. The expression of CK1/10 in the epithelial basal and suprabasal layers was significantly higher in OLP than in fibromas. There was no demonstrable staining for CK7/18 in either OLP or fibromas. A significant correlation was evident between the expression of HSP60 and CK1/10 in the basal epithelial cells in OLP. The findings support a role for HSP60 in the pathogenesis of OLP. A unifying hypothesis of the pathogenesis of OLP, involving two sequential immune reactions, is proposed.

Solitary fibrous tumor of the spinal cord. Report of a case with scrape cytology

BACKGROUND

Solitary fibrous tumor is a rare spindle cell tumor and has been forced at a variety of sites. To the best of our knowledge, only two cases of solitary fibrous tumor arising in the spinal cord have been reported; no cytologic findings were documented.

CASE

A 62-year-old male presented with a spinal cord tumor. A scrape smear of the resected tumor revealed naked, spindle-shaped nuclei. Some nuclei were twisted or had long spindles. In the background, abundant, thin and thick collagen fibers were present. Immunohistochemically, the spindle cells were positive for CD34 and negative for S-100 protein and alpha-smooth muscle actin. Histologic diagnosis of the tumor was benign solitary fibrous tumor.

CONCLUSION

Our case indicates that solitary fibrous tumor can occur in the spinal cord and should be differentiated from other benign spindle cell tumors, such as meningioma and schwannoma. The key cytologic features of solitary fibrous tumor may be the presence of abundant thin and thick collagen fibers in scrape specimens.

Scrape cytology of elastofibroma. Report of a case with diagnostic cytologic features

BACKGROUND

Elastofibroma is a benign, soft tissue tumor that occurs most frequently in the subscapular area in elderly people. To the best of our knowledge, in only two cases has the cytology been reported. The aim of this report is to describe the characteristic cytologic findings of elastofibroma and to discuss the usefulness of elastin stain in scrape smears.

CASE

A 72-year-old female had bilateral masses in the lower subscapular area. Scrape smears from a cut surface of the resected masses revealed abundant, "wormlike" or "braidlike" material with central cores with Papanicolaou stain in an intraoperative consultation. Various-sized, petaloid or crystalloid globules were also present. Those elastic fibers were strongly positive for elastin stain in cytologic preparations.

CONCLUSION

Elastofibroma can be diagnosed cytologically, and elastin-stained, scrape cytologic preparation is especially useful in such a case.

Myxoid solitary fibrous tumor: a study of seven cases with emphasis on differential diagnosis

Focal myxoid change is a well-recognized feature of solitary fibrous tumor (SFT), but to date, predominantly myxoid examples of SFT have not been reported. We describe seven cases of SFT in which stromal myxoid change affected 50% or more of the tumor examined, thus obscuring typical diagnostic features. Patients ranged in age from 35 to 68 years old (median, 45 yr), with an equal sex distribution. Tumor locations included pleura, orbit, and periparotid subcutaneous tissue, as well as four cases in deep soft tissue (two in the abdominal wall and one each in the chest wall and thigh). Myxoid areas were identified grossly in four cases. Histologically, the lesions were composed of bland spindle cells disposed haphazardly or with a lacy or reticulated appearance in a myxoid, richly vascularized stroma These myxoid areas were punctuated by small cellular aggregates in four cases, and areas showing diagnostic features of SFT were present in five of seven primary excision specimens. Atypical features suggestive of malignancy were not present in any of the cases. Immunohistochemically, all of the seven cases stained positively for CD34 and CD99 (013), and all were negative for smooth muscle actin, desmin, S-100 protein, epithelial membrane antigen, and pan-keratin. There were no recurrences or metastases reported in four patients with limited follow-up (median duration, 19 mo). Recognition of this uncommon morphologic subset of SFT is important because of possible confusion, particularly in small biopsy specimens, with a variety of myxoid spindle cell neoplasms with different biologic potential. These include low-grade fibromyxoid sarcoma, myxoid synovial sarcoma, malignant peripheral nerve sheath tumor, low-grade myxofibrosarcoma, myxoid liposarcoma, myxoid spindle cell lipoma, myxoid neurofibroma, and so-called "hemangiopericytoma."

Plantar fibromatosis: an immunohistochemical and ultrastructural study

The analogies between plantar fibromatosis and Dupuytren's disease (palmar fibromatosis) are well known. The latter is clinically more frequent and has been the object of extensive immunohistochemical and ultrastructural studies, with a view to investigating its pathogenesis. By contrast, such data on plantar fibromatosis are quite scarce. A histochemical, immunohistochemical, and ultrastructural study was performed on nodule tissue from six patients who were subjected to total fasciectomy for plantar fibromatosis. The study of myofibroblasts revealed features suggestive of their fibroblastic origin and evidenced a cytoskeleton and an extracellular filamentous system that could enable myofibroblasts to generate and exert the intracellular forces that contribute to the contraction of the aponeurosis. These aspects are similar to those observed in Dupuytren's disease and seem to lend support to the theory that the two diseases are expressions of the same disorder.

Hypoglycaemia associated with a solitary fibrous tumour of the pleura

We report the interesting case of an elderly woman who presented with hypoglycaemic episodes and weight loss. She was found to have a solitary fibrous tumour weighing more than 1.7 kg arising from the diaphragmatic pleura, which had been producing insulin-like growth factor II. After surgical removal of this well-encapsulated, pedunculated tumour her hypoglycaemia resolved and she returned to normal both clinically and biochemically.

Atypical and malignant solitary fibrous tumors in extrathoracic locations: evidence of their comparability to intra-thoracic tumors

Solitary fibrous tumor (SFT), first described as a pleural lesion, has been reported at numerous extrathoracic sites over the past 10 years. About 10% to 15% of intrathoracic SFTs are histologically or clinically malignant, but such cases have very rarely been described at other locations. Among 92 cases of extrathoracic SFT in our files, we identified 10 that either had recurred (2 cases) or had a least one atypical histologic feature (8 cases). The ten tumors occurred in five men and five women, 32 to 81 years old (median 56), measured 1.9 cm to 20 cm (median 11.5 cm), and were located in the abdomen/pelvis (4 cases), retroperitoneum (3 cases), groin, trunk, and upper arm. Nuclear atypia (8 cases), markedly increased cellularity (6 cases), areas of necrosis (4 cases), and greater than 4 mitoses/10 HPFs (3 cases) were seen in addition to the typical histologic features of SFT. Six tumors had at least two of these atypical histologic features. Nine cases were positive for CD34, six were positive for O-13, and one was focally positive for smooth muscle actin. Eight were excised completely. Subsequent follow-up revealed tumor relapse in eight cases (follow up 6-180 months, median 24). Four patients had local recurrence at 12 to 168 months. Distant metastasis developed at 1 to 6 years in five cases with spread to lung (2 cases), liver (4 cases), and bone. Metastasis or local recurrence developed within 2 years in five patients. To date, no patient has died of their tumor. These findings demonstrate that nuclear atypia, hypercellularity, greater than 4 mitoses/10 HPFs, and necrosis may be seen in up to 10% of extrathoracic SFTs, and are associated with, but are not by themselves predictive of, aggressive clinical behavior. In addition, our findings confirm that the behavior of extrathoracic SFTs is unpredictable, entirely comparable to that of their better known pleural counterparts, and confirm that patients with SFTs in all locations require careful, long-term follow up. It is probably unwise to regard any such lesion as definitely benign.

Calcifying aponeurotic fibroma: a clinicopathologic study of 22 cases arising in uncommon sites

Calcifying aponeurotic fibroma is a rare soft tissue tumor that primarily occurs in children and adolescents and has a strong predilection for the distal portion of the extremities, especially the hands and feet. This report describes 22 previously unpublished cases arising in uncommon sites. Fifteen patients were male, and seven were female (age range, 2 to 43 years; median age, 9 years). The process typically presented as a painless mass and was present from 2 weeks to 11 years before resection. Sites of involvement were the back (n=8), knee region (n=5), thigh (n=3), forearm (n=3), elbow (n=2), and arm, not otherwise specified (n=1). The lesions were often adherent to dense fibrous connective tissue (eg, tendon, fascia, or periosteum) and ranged from 1.0 to 5.0 cm in maximum dimension. The process typically had an irregular contour and a firm, fibrous consistency. Sometimes minute foci with a calcific appearance were evident grossly. Microscopic examination showed spindled fibroblasts with a fascicular growth pattern and scattered epithelioid cells bordering chondroid foci with or without mineralization. Immunoreactivity was present for vimentin (six of six), muscle-specific actin (three of six), smooth muscle actin (three of six), CD99 (five of five), CD34 (one of six), CD57 (one of six, trace), EMA (two of six, trace), S100 protein (five of six), CD68 (five of five), and progesterone receptor (one of six). The tumors were managed by local excision (n=20), incomplete local excision (n=1) and biopsy only (n=1). Follow-up information was available for 10 patients with a median follow-up interval of 94 months. Five patients (50%) developed one or more recurrences. Familiarity with this entity should help to avoid confusion with other processes, including infantile and extraabdominal fibromatoses, a chondroma of soft parts, and a fibrous hamartoma of infancy.

Juvenile hyaline fibromatosis: ultrastructural study

Juvenile hyaline fibromatosis is a multisystemic disorder characterized by a triad of cephalic fibrous outgrowths, gingival hyperplasia, and flexion contractures. The aim of this study was to find new ultrastructural features that could be useful for differentiating this entity from other types of fibromatosis. Mucosal lesions processed for light and electron microscopy by routine techniques showed hyperactive-appearing spindle-shaped fibroblasts and dysplastic mesenchymal cells. Dilated rough endoplasmic reticulum, prominent Golgi complexes, and multivesicular bodies as well as single membrane vesicles filled with fibrillogranular material were seen within the cytoplasm of dysplastic mesenchymal cells. Many fibrillogranular vesicles contained smaller vesicles. There were also invaginations of the cell membrane that contained fibrillogranular material similar to that seen in the single membrane vesicles, suggesting engulfment of an extracellular substance. The stroma contained both normal and serrated collagen fibrils, microfibrils, and two types of fibrillogranular material, one of them with a characteristic banding pattern. Our clinical and histopathologic findings resemble those previously described in cases of infantile systemic hyalinosis and juvenile hyaline fibromatosis. So many features of these two conditions overlap that it is difficult not to consider them as parts of a spectrum of the same disorder.

Inhibin expression in ovarian tumors and tumor-like lesions: an immunohistochemical study

We investigated 203 ovarian tumors and tumor-like lesions for inhibin expression using a monoclonal anti-inhibin alpha antibody. Inhibin was present in the tumor cells in all 14 primary adult granulosa cell tumors (4 luteinized) plus 3 metastatic, all 10 primary juvenile granulosa cell tumors plus 1 metastatic, 10 of 11 thecomas, 3 of 11 fibromas, 4 of 11 sclerosing stromal tumors, 6 of 11 Sertoli cell tumors (1 oxyphilic), 7 of 11 Sertoli-Leydig cell tumors, 1 gynandroblastoma, 10 primary ovarian sex cord tumors with annular tubules plus 2 metastatic, 8 of 9 steroid cell tumors, both pregnancy luteomas, 1 of 2 unclassified sex cord tumors, 2 of 5 gonadoblastomas, 9 of 10 female adnexal tumors of probable wolffian origin, and in the non-neoplastic stroma of many carcinomas and germ cell tumors. The tumor cells were inhibin-negative in 10 fibrosarcomas, 12 small cell carcinomas of hypercalcemic type, 24 germ cell tumors (except for a focus of inhibin-positive syncytiotrophoblast in one case), and 17 ovarian carcinomas. Two of the three inhibin-positive fibromas showed diffuse immunostaining and were associated with evidence of estrogenic activity. Among nine Sertoli-Leydig cell tumors with available clinical data, four that were more than minimally inhibin-positive were accompanied by androgenic manifestations; five inhibin-negative or only minimally positive tumors lacked such evidence. Inhibin immunostaining may be useful in the differential diagnosis of inhibin-positive sex cord tumors versus histologically similar inhibin-negative neoplasms, but inhibin negativity does not preclude a diagnosis of sex cord tumor. The unexpected, common inhibin positivity of female adnexal tumors of probable wolffian origin indicates that inhibin staining cannot be used to differentiate these tumors from Sertoli cell tumors. Inhibin immunostaining is also helpful in identifying potential steroid hormone-secreting cells in the non-neoplastic stromal component of epithelial, germ cell, and other ovarian tumors.

[Microstructure of subcutaneous lesions in juvenile hyaline fibromatosis]

Juvenile hyaline fibromatosis is a rare autosomal recessive interstitial disease characterized by nodes and tumours of skin and soft tissues as well as by gingival hyperplasia. The authors described a case of 28-year-old male based on histopathological diagnosis. The patient was admitted to the hospital thrice in his life with the diagnosis of arthrogryphosis. Last time he presented with extensive secondary impetigo in extremities and pachydermia, polymalformation syndrome, multiple subcutaneous tumours, gingival hypertrophy, contractures, osteolytic lesions and positive family history. In histology, tumoriform lesions showed a structureless hyaline matrix often with chondroosseous metaplasia and calcium salts. More or less numerous cells in the matrix had a fibroblastoid appearance with eosinophilic cytoplasm, oval nuclei and frequently pericytoplasmic halo. Electron microscopy revealed dilated cisterns of rough endoplasmic reticulum and a hypertrophied Golgi apparatus. Particles representing calcium salts according to their density were rare. Immunohistochemistry of tumour cells showed vimentin, alpha-1-antichymotrypsin and alpha-1-antitrypsin. The findings concurred with the literature in which, nevertheless, the immunohistochemical picture were not mentioned.

Benign fibromatous tumor (fibroma) of the kidney: a case report

Benign fibromatous tumor (fibroma) of the urogenital tract is a distinctive pathologic entity occurring in the testis, paratesticular structures and renal peripelvis. We report a well-circumscribed tumor replacing the cortex and the medulla of more than half of the upper kidney, radiographically thought to be renal cell carcinoma. Histologically, the tumor was characterized by a variable cellularity and was composed of bland spindle-shaped cells loosely dispersed in a fibromyxoid to densely fibrous stroma in which calcifications and chronic inflammation were not observed. Immunocytochemistry showed that cells were positive for vimentin and, only focally, stained positive for desmin and alpha-smooth muscle actin. Differential diagnosis included a wide spectrum of benign and malignant spindle cell tumors. The clinicopathologic features were consistent with benign fibromatous tumor (fibroma) of the kidney. To our knowledge, this is the first case of benign fibromatous tumor (fibroma) of the kidney reported in the English literature.