Yutaka Daimaru

A clinicopathologic and immunohistochemical study of gastrointestinal stromal tumors

The clinicopathologic and immunohistochemical features in 120 cases of gastrointestinal stromal tumor (GIST) were reviewed. Excluding 24 cases of gastric schwannoma, 96 cases of GIST consisting of 62 benign tumors and 34 sarcomas (low grade, 17; high grade, 17), with 9 cases arising in the esophagus, 57 in the stomach, 28 in the small intestine, and 2 in the colon, were studied. All esophagus and colon tumors were benign and resembled a conventional leiomyoma histologically. However, the gastric and small intestine benign tumors mostly showed histologic features of cellular or epithelioid leiomyoma. Immunohistochemically, desmin caused a positive reaction in all esophagus and colon tumors, but only 26% of gastric and small intestine tumors. However, muscle‐specific actin (HHF35) caused a positive reaction in most GIST (92%). The 10‐year survival rates of the patients with gastric sarcoma and those with intestinal sarcoma were 74% and 17%, respectively. These results showed that histologic and immunohistochemical features were distinctly different, depending on the location in the gastrointestinal tract; that most GIST, excluding schwannoma, had smooth muscle differentiation; and that sarcomas had a more favorable prognosis when they occurred in the stomach rather than the intestine. Cancer 1992; 69:947–955.

Benign Schwannoma of the gastrointestinal tract: a clinicopathologic and immunohistochemical study

A clinicopathologic and immunohistochemical review was made of 24 cases of distinctive nerve sheath tumors located in the gastrointestinal tract. The tumors were microscopically evident in the presence of peripheral lymphoid cuffing and benign nuclear atypia. The tumors arose in the muscularis propria of the stomach in 23 cases and in the ascending colon in 1 case. The patients included 9 men and 15 women whose ages ranged from 36 to 78 years (average, 58). No recurrence has developed in any patient who underwent resection. Although positive immunostaining for S-100 protein, Leu 7 antigen, and laminin might support the schwannian nature of these tumors, the positive immunoreactivity for glial fibrillary acidic protein (GFAP) indicated the possibility of a myenteric plexus origin. The pattern of S-100 protein immunostaining differed from that seen in cases of gastrointestinal stromal tumors associated with von Recklinghausens neurofibromatosis or that noted in cases of conventional leiomyomas. We propose that these tumors be designated as benign schwannoma of the gastrointestinal tract.

Leiomyosarcoma of the external soft tissues. A clinicopathologic, immunohistochemical, and electron microscopic study

This clinicopathologic study concerns 25 cases of leiomyosarcoma of the external soft tissues, including an immunohistochemical survey of 19 cases and an electron microscopic examination of six. There was a female preponderance in a ratio of 16:9. The most common site of tumors was the thigh (nine cases), followed by the knee (five cases). Three tumors were located in the dermis, 9 were confined down to the subcutis, 2 involved the deep fascia, and 11 involved the skeletal muscle. Superficially located tumors were smaller than deeply located ones. According to the predominant histologic features, the tumors were classified into well (6), moderately (14), and poorly (5) differentiated. In addition to the classical microscopic features, dedifferentiated areas resembling malignant fibrous histiocytoma were noted in three primary tumors and one recurrent tumor. In six tumors, the anatomical location and histologic features were highly suggestive of leiomyosarcoma arising in the venous wall. Many tumor cells immunoreactive for actin were seen in 13 and for desmin in 9 of the 19 cases. Four tumors contained a few tumor giant cells positive for alpha‐1‐antichymotrypsin. Ultrastructurally, the tumors were characterized by smooth muscle tumor cells showing a spectrum of differentiation of varying degrees. In two cases, histiocyte‐like tumor cells were detected. The most reliable prognostic parameter was the depth of the initial tumors; all patients with a leiomyosarcoma confined down to the subcutis are living, most of them more than 5 years after excision, whereas seven of the nine patients with a tumor involving the muscle have died within 5 years after excision.

Malignant neuroepithelioma (peripheral neuroblastoma). A clinicopathologic study of 15 cases.

A clinicopathologic study of 15 cases of malignant neuroepithelioma (peripheral neuroblastoma) of soft tissues is reported. The patients were chiefly young Japanese adults with a median age of 21 years. The tumors arose mainly in the soft tissues of the lower extremity (seven cases) and the trunk (four cases). Microscopically, there were sheets of closely packed, small round or oval cells, and Homer Wright-type rosettes were seen in all cases, one of which also had Flexner-type rosettes. Immunohistochemical cytoplasmic localization of neuron-specific enolase (NSE) was demonstrated in six of the eight cases, using the peroxidase-antiperoxidase (PAP) method. In no case, however, was there any staining reaction for S-100 protein. Of the 14 patients for whom follow-up information could be obtained, nine died within a period of 2 years and two were alive and well for over 5 years after the initial treatment. Differential diagnosis from other soft-tissue round-cell sarcomas, such as embryonal or alveolar rhabdomyosarcoma, extraskeletal Ewings sarcoma, and others, are briefly discussed, on a clinicopathologic basis.

Malignant soft tissue neoplasms with the histologic features of renal rhabdoid tumors: An ultrastructural and immunohistochemical study

Five round cell neoplasms of the soft parts that histologically resembled malignant rhabdoid tumors of the kidney were studied. The tumors were composed mainly of poorly differentiated round or, sometimes, polygonal cells, with a minority of elongated cells; the cytoplasm of many of the cells contained filament-laden acidophilic inclusions. Ultrastructurally, the intracytoplasmic structures were seen to consist of aggregates of 10-nm intermediate filaments, and immunohistochemical staining revealed the presence of cytokeratin and vimentin. All five patients with this tumor had an aggressive clinical course; three of the patients died shortly after the initial diagnosis. As this tumor does not seem to be linked to any known entity, it is referred to as malignant rhabdoid tumor of the soft parts and could be a heterogeneous entity.

Malignant peripheral nerve-sheath tumors (malignant schwannomas). An immunohistochemical study of 29 cases.

ABSTRACTTwenty-nine cases of malignant schwannoma consisted of three groups; 11 tumors associated with von Recklinghausens disease (group I), nine tumors arising grossly from nerve trunks (group II), and 11 tumors so diagnosed basically on the histologic features (group III). Using the immunoperoxidase methods, the tumors were investigated with regard to S-100 protein, keratin, and epithelial membrane antigen (EMA). Approximately one-third of the cases (10 of 29) were devoid of S-100 positive cells and the remaining two-thirds (19 of 29) contained positive cells, with variable frequencies. The number of S-100 positive cells differed, depending largely on the presence or absence of neurofibroma-like areas in the tumor. The positive cells were rarely found in the group III tumors, which were neither associated with von Recklinghausens disease nor connected to nerve trunks, even when their histologic features were unequivocal. Certain specific organoid structures in the tumor, such as neuroid or tactoid ones, were positive for S-100 protein. In one of the two malignant epithelioid schwannomas, the tumor cells were strongly positive for S-100 protein, thereby suggesting melanocytic differentiation. This tumor was interpreted as a melanocytic malignant schwannoma rather than a malignant melanoma, based in part on the fact that the overlying epidermis was uninvolved in this patient with von Recklinghausens disease. True epithelial differentiation in one case of glandular schwannoma was verified by the positive stain of EMA along the inner surface of the glandular element.

The existance of rhabdoid cells in specified soft tissue sarcomas

We report the occurrence of rhabdoid cells in several specified soft tissue sarcomas of round cell variety. The rhabdoid cells had an acidophilic cytoplasm containing a globular perinuclear inclusion and were characterised ultrastructurally by the presence of aggregates of 10 nm intermediate filaments. These filaments contained both cytokeratin and vimentin, as demonstrated immunohistochemically. Extensive sampling of soft tissue sarcomas revealed the presence of such cells in different types of soft tissue round cell sarcomas as follows: 12 of 13 cases of epithelioid sarcomas, 8 of 13 synovial sarcomas (composed predominantly of round cells), 6 of 20 extraskeletal myxoid chondrosarcomas and 4 of 4 round celled malignant mesotheliomas. We wish to stress that the appearance of rhabdoid cells is not a monopoly of one particular type of tumour.

S-100 protein distribution in liposarcoma An immunoperoxidase study with special reference to the distinction of liposarcoma from myxoid malignant fibrous histiocytoma

The presence and distribution of S-100 protein were studied in 63 cases of liposarcoma and 20 cases of myxoid malignant fibrous histiocytoma (MFH), using the immunoperoxidase technique. Normal adipose tissue and benign lipomatous tumours were also studied by the same technique, for purposes of comparison. In all liposarcomas, most of the adipocytes and vacuolated lipoblasts were positive for S-100 protein, although the tumour cells in non-lipogenic areas of dedifferentiated liposarcoma and the non-vacuolated giant cells with a deeply eosinophilic cytoplasm in the pleomorphic liposarcomas were devoid of S-100 protein immunoreaction products. One third of the myxoid type liposarcomas contained numerous immunoreactive, immature-appearing spindle or oval cells, reminiscent of the primitive fat organs of white adipose tissue. Conversely, none of the myxoid MFHs contained S-100 protein in the tumour cells, including the irregularly vacuolated ones. These results suggests that the immunohistochemical demonstration of S-100 protein is a useful diagnostic tool, particularly for the assessment of vacuolated tumour cells and for the diagnosis of myxoid tumours.

Epithelial profile of epithelioid sarcoma. An immunohistochemical analysis of eight cases

Eight cases of epithelioid sarcoma were examined immunohistochemically, in order to clarify the adjunct epithelial profile of the tumor and to ascertain the intermediate filaments contained in the tumor cells. All tissues showed a strongly positive immunoreactivity for epithelial membrane antigen (EMA) and tissue polypeptide antigen (TPA). In the case of carcinoembryonic antigen (CEA), one showed a strong reaction, whereas the others were variably less stained. Cytokeratins (45 kd and 54 kd) specific for simple epithelia, including coelomic epithelium, were regularly found in all cases; a small number of cells were positive for high molecular weight cytokeratin (57 kd) and none for 66 kd cytokeratin. Coexpression of both cytokeratin and vimentin was confirmed using fresh‐frozen materials. Therefore, both microscopic and immunohistochemical evidence supports the hypothesis that epithelioid sarcoma masquerades as a carcinoma. Cancer 59:134–141, 1987.

Intramuscular myxoma: a clinicopathologic, immunohistochemical, and electron microscopic study

This Clinicopathologic study concerns 17 cases of intramuscular myxoma, including an immunohistochemical survey of 10 cases and an electron microscopic examination of 4. There was a female preponderance in a ratio of 14:3. The most common sites of tumors were the large muscles of the thigh (seven cases), followed by those of the buttock (three) and the lower leg (three). The size of the tumor ranged from 1.5 to 20 cm (median, 6 cm) in the greatest diameter. Neither recurrence nor metastasis was seen in any of 15 patients for whom information was available. In addition to the conventional microscopic features, such as hypocellularity, absence of a plcxiform capilliary network, and no detection of typical glycogenrich lipoblasts, the following findings were regarded as helpful to differentiate an intramuscular myxoma from myxoid liposarcoma: (1) hypovascularity of the tumor, demonstrated by angiography; (2) a homogeneous computed tomography appearance with low density, (3) absence of S‐100 protein immunoreactive cells such as lipoblasts; and (4) electron microscopically, the constituent cells were predominantly fibroblastlike cells with a prominent secretory activity, together with a small number of primitive mesenchymal cells and histiocyte‐like cells, but with no lipoblasts. After simple excision, the 15 patients who could be followed are well with no recurrence during various periods of follow‐up.Cancer 58:740‐747, 1986.