[Successful operation on giant solitary fibrous tumor of the pleura]

A 68-year-old man began complaining of dizziness and dyspnea on exertion 2 months ago. Chest X-ray and CT scan taken on admission revealed a giant tumor occupying almost all of the right thoracic cavity. The mediastinum, especially RA and IVC, was markedly oppressed and shifted by the tumor. MRI showed no invasive lesions of the tumor into adjacent organs. An operation was performed under the tentative diagnosis of solitary fibrous tumor (SFT) of the pleura by transcutaneous needle biopsy. The tumor was encapsulated and resected from the lower lobe of the right lung using a surgical stapler. Then the tumor was carefully dissected from the chest wall, pericardium and diaphragma, and removed completely. It weighed 3920 g and measured 22 x 20 x 20 cm. Various immunohistochemical properties of the specimen were morphologically compatible with SFT. The postoperative course was uneventful and the patient is now free of complaints. Because malignant cases of SFT have been reported a careful follow-up will be performed.

Solitary fibrous tumor of the skin

Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm that most commonly involves the pleura, but is increasingly more often observed in extrapleural locations. A 37-year-old woman presented with an SFT involving the skin and subcutaneous tissue of the scalp. Histologically, SFT is well circumscribed and composed of uniform spindle cells arranged in interlacing fascicles. It exhibits alternating hypercellular and hypocellular areas with abundant thick, often keloid-like, hyalinized collagen. Hemangiopericytoma-like areas are frequently prominent. Immunohistochemical markers for smooth muscle, neural, and epithelial differentiation are negative, but generalized positivity for CD-34 is characteristic. Because of the expanding spectrum of anatomic involvement of SFT, it is not surprising that on rare occasions this tumor may involve the skin.

Solitary fibrous tumor of urinary bladder: report of two cases

The clinical and pathologic features of two cases of solitary fibrous tumor arising from urinary bladder wall are described. To our knowledge, solitary fibrous tumors have not been previously reported at this site. Both tumors showed typical histologic features of solitary fibrous tumor, were CD34 immunostain positive and pursued a benign clinical course on short term follow-up.

Solitary fibrous tumour: clinicopathological, immunohistochemical, and ultrastructural analysis of 12 cases arising in soft tissues, nasal cavity and nasopharynx, urinary bladder and prostate

The clinicopathological features of 12 extraserosal solitary fibrous tumours (SFT) are described. The age of the patients ranged from 18 to 72 years (mean: 48.2 years; median: 54 years); 5 were female patients. Seven lesions arose in soft tissue (5 in perifascial, and 1 each in subcutaneous and intramuscular tissues). They were situated in the groin (2 cases) and the neck, right buttock, left scapula, upper arm, and anterior abdominal wall (1 case each). One polypoid lesion was seen in in the nasal cavity and 1 in the nasopharynx; 2 neoplasms arose in the urinary bladder and 1 was located in the prostate and periprostatic tissue. Nine lesions were excised; in 1 patient wide excision was performed and in 2 patients, transurethral resection. Limited follow-up of 3 cases revealed a benign clinical course. The size of the neoplasms ranged from 1.7 cm to 20.0 cm (mean: 5.4 cm; median: 3.5 cm). Histologically, the neoplasms were well circumscribed and composed of cytologically bland spindle cells arranged without an obvious pattern; focally storiform or fascicular growth patterns were seen. Tumour cells were separated by thick bands of collagen demonstrating foci of keloid-like hyalinization. Prominent vascularity showing a haemangiopericytoma-like vascular pattern and vessels with thick, hyalinized vessel walls were seen in all cases. Increased mitotic activity was noted in 2 soft tissue cases (4-6 mitoses in 10 high-power fields); the other cases showed fewer than 2 mitotic figures in 10 highpower fields. Immunohistochemically, all cases tested stained positively for vimentin, CD34 and CD99, and 2 cases showed focal myofibroblastic differentiation. Two cases examined ultrastructurally showed a fibroblastic phenotype; focally pinocytic vesicles and microfilaments were identified. SFT represents a distinct neoplasm that should be included in the differential diagnosis of spindle-cell neoplasms in soft tissue, nasal cavity and nasopharynx, urinary bladder, and prostate. Strict diagnostic criteria are necessary to avoid overdiagnosis or confusion with more aggressive neoplasms in these locations.

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.

Solitary fibrous tumor involving the renal capsule

Solitary fibrous tumors are spindle-cell neoplasms that originally were described in the pleura but that can occur in a large variety of sites. We report a well-circumscribed tumor, apparently involving the renal capsule, clinically thought to be a renal-cell carcinoma or oncocytoma. It was composed of bland spindle-shaped cells with a patchy lymphoplasmacytic infiltrate, suggesting sarcomatoid renal-cell carcinoma, inflammatory myofibroblastic tumor, or solitary fibrous tumor; however, immunohistochemical stains were negative for keratin, alpha-smooth-muscle actin, and desmin but strongly positive for CD34. Ultrastructural examination revealed fibroblast-like cells without myofibroblastic or epithelial differentiation. The combined findings favor a diagnosis of a solitary fibrous tumor involving the renal capsule. To our knowledge, this lesion has not been reported in this location.

Solitary Fibrous Tumor Pleura

The Solitary Fibrous Tumour of Pleura has rarely been observed. A new case has been reported. This tumour is often asymptomatic and mostly discovered by chance. A well delimited and round opacity is demonstrated on the chest X-ray. computerized tomography confirms the fleshy nature of this tumour with inhomogeneous enhancement. The treatment is a complete surgical excision. The prognosis is excellent, if diagnosed early.

Plexiform xanthomatous tumor. A report of three cases

We describe three cases of plexiform xanthomatous tumor in middle-aged men. The tumors shared some morphological features with xanthoma, cholesterotic fibrous histiocytoma, and plexiform fibrohistiocytic tumor. However, no hyperlipoproteinemia was found in our cases, and many morphological features distinguish the plexiform xanthomatous tumor from all the other entities.

Expression of CD34 by solitary fibrous tumors of the pleura, mediastinum, and lung

Solitary fibrous tumors are rare neoplasms that most commonly involve the pleura, mediastinum, and lung. Because they lack distinctive histologic features, immunologic staining has frequently been employed to exclude other neoplasms in the differential diagnosis. Their reported phenotype to date is generally negative, notably for muscle-type actins, desmin, keratin, and S-100 protein. Although this testing is of some help, it does not serve to distinguish all processes in the differential diagnosis, and when it does, it places too great an emphasis on a negative finding to make a diagnosis. We report here that CD34 monoclonal antibodies reacted with 11 of 14 solitary fibrous tumors in paraffin sections. Thus, they provide a positive marker that distinguishes the solitary fibrous tumor from most elements in the differential diagnosis.

Ossifying fibromyxoid tumor of soft parts: a morphological and immunohistochemical study

A case is presented of ossifying fibromyxoid tumor of soft parts (OFMTSP) which occurred in the left cheek of a 59 year old Chinese woman. Histologically, the tumor was located in the subcutis with a fibrous pseudocapsule that contained discontinuous rims of mature trabecular bone. The tumor cells were small, round to ovoid with a uniform, round nucleus and a pale or slightly eosinophilic cytoplasm. Most of the cells were arranged in a random manner, some in a vague lace-like pattern. Mitotic figures were extremely rare. The stroma appeared fibromyxoid with scattered foci of mucinous lakes. Immunohistochemically, most of the neoplastic cells displayed immunoreactivities for S-100 protein, S-100 protein alpha, vimentin and alpha-smooth muscle actin; many tumor cells were positive for desmin. The tumor also showed stromal immunoreactivity for type IV collagen and was negative for cytokeratins, epithelial membrane antigen, glial fibrillary acidic protein, neurofilaments, muscle-specific actin, Leu-7, myelin-basic protein, osteocalcin and melanoma-specific antigen. The immunophenotypes expressed by the present OFMTSP seem to reflect two lineages of neoplastic cell differentiation, that is of nerve sheath and of smooth muscle; at the present stage, it is premature to diagnose this lesion as either nerve sheath or smooth muscle tumor.

Primary mesenchymal tumors of the urinary bladder. A histological and immunohistochemical study of 30 cases

The light microscopic and immunohistochemical features of 30 primary mesenchymal neoplasms of the urinary bladder are reported. Half of the cases represented smooth and striated muscle tumors (five leiomyomas, seven leiomyosarcomas including epithelioid and myxoid subtypes, one rhabdomyoma, one embryonal rhabdomyosarcoma and one alveolar rhabdomyosarcoma). One third of the tumors were of fibrohistiocytic origin (one fibrous histiocytoma and eight malignant fibrous histiocytomas including fascicular and storiform, inflammatory and pleomorphic subtypes). In addition, a malignant epithelioid schwannoma, a round cell liposarcoma, two hemangiomas and two mixed mesodermal tumors were observed. The morphology of the vesical mesenchymal tumors was identical to that of their counterparts known to occur in other sites, particularly in the soft tissue. Muscle-specific actin, alpha-1-antichymotrypsin, S-100-protein and neuron-specific enolase proved to be useful and reliable immunomarkers for differential diagnosis of poorly differentiated leio- and rhabdomyosarcomas, malignant fibrous histiocytomas and malignant schwannomas. Since some tumors coexpressed several classes of intermediate filaments, diagnostic immunocytochemistry should only be used considering a larger panel of antibodies and in close correlation with the histological and cytological features of the neoplasms.

Malignant solitary fibrous tumor of the pleura

We describe a case of malignant solitary fibrous tumor of the pleura in a 15-year-old female who presented clinically with back pain. Grossly, the tumor had a pedicle attached to the pleura and histologically showed proliferating spindle-shaped cells with a high mitotic index. Immunohistochemical and ultrastructural features were consistent with a tumor of fibroblastic origin. Flow cytometric DNA analysis revealed an aneuploid population among the tumor cells.

Desmoplastic variant of ameloblastoma in Malaysians

Seventeen cases are reported of desmoplastic variant of ameloblastoma of the jaws observed during the years 1967-1991. There were 12 females and 5 males, and these consisted of 7 Chinese, 6 Malays, 2 Indians, 1 Sikh and 1 Kadazan. Their ages at diagnosis ranged from 21-60 years with a mean of 36.6 years. There were 10 mandibular and 7 maxillary tumours. Of these, 14 cases involved the anterior segment with extension to the premolar region in 5 cases. 60% of cases were radiologically suggestive of fibro-osseous lesions. The main mode of treatment was resection and 1 case presented with recurrence. The findings of this study were compared with those of previous reports.

Mesenchymal, non-meningothelial tumors of the central nervous system

The spectrum of non-meningothelial mesenchymal tumors that may arise within the central nervous system is presented, based on the current classification of soft tissue tumors. Among malignant types, hemangiopericytoma, rhabdomyosarcoma, mesenchymal chondrosarcoma, and malignant fibrous histiocytoma are the most frequent ones. Rare tumor entities are mentioned. As in soft tissue sarcomas, diagnosis is mainly based on light and electron microscopy, while immunohistochemistry can improve accuracy of diagnosis.