Ultrastructural Study of a Perineurioma

A case of soft tissue tumor in the left brachialis muscle of a 49-year-old Japanese female patient was studied by electron microscopy. The tumor was diagnosed as intramuscular myxoma by light microscopy, but electron microscopic observation revealed that the tumor almost entirely consisted of cells similar to normal perineurial cells. The tumor cells possessed long, slender cytoplasmic processes covered by well-developed but discontinuous basal laminae, clusters of pinocytotic vesicles, and infrequent intercellular junctions. Perineurial cells have also been observed in other peripheral nerve lesions: neurofibromas, nerve sheath myxomas, and localized hypertrophic neuropathies. However, the term “perineurioma” or “perineurial cell tumor” should be reserved for discrete tumorous masses that are almost entirely composed of perineurial cells without evidence of residual axons, Schwann cells, fibroblasts, or tactile corpusclelike structures. Perineurioma may represent a third category of peripheral nerve sheath tumors, ultrastruc-turally distinct from schwannomas and neurofibromas.     

Ultrastructural Study of a Clear Cell Chondrosarcoma

A lesion in the left humeral head of a 15-year-old Japanese boy was light-microscopically diagnosed as clear cell chondrosarcoma. Fresh tissues from the lesion were studied ultrastructurally. In most tumor cells, that is, clear cells, paucity of organelles, sparse free ribosomes, and low protein content in cytosol were most striking. Tumor cells had many microvilli characteristic of cartilage cells. Among scanty organelles, vesicles or cisternae of dilated rough endoplasmic reticulum were rather conspicuous, and well-developed Golgi complexes were sparse. Intercellular matrix was scanty. These results suggest that intercellular matrix substance may be synthesized substantially by rough endoplasmic reticulum, whereas the synthesized substance perhaps cannot be transported smoothly into extracellular spaces because of scanty well-developed Golgi complexes.     

Ultrastructural Study of a Perineurioma with Ribosome-Lamella Complexes

The participation of the perineurial cell in peripheral nerve tumors is the subject of much debate. The case of a 75-year-old female with a soft tissue tumor on her left shoulder is presented. The tumor had histological, ultrastructural, and immunohistochemical characteristics of a pure perineurial cell neoplasm. Ultrastructurally, distinctive ribosome-lamella complexes were found in the cytoplasm of the perineurial cells. This may be the first time that these structures have been described in perineurioma.     

Perineurial Cell Differentiation in Benign Tumors and Tumorlike Proliferation of Peripheral Nerves

An unusual, benign, spindle cell peripheral nerve sheath tumor (PNST) is reported that on ultra-structural examination was composed only of perineurial cells. The neoplastic cells showed positive immunoreactivity for S-100 protein and negative immunoreactivity for epithelial membrane antigen; this is not the expected immunophenotype of a perineurioma. Continued examination of benign PNSTs using electron microscopy and immunohistochemistry has the potential to reveal additional variations in the cellular composition and immunophenotype of these soft tissue tumors. PNSTs such as the one described will renew the debate about the cytogenesis of the perineurial cell and its role in PNSTs.     

Perineurial Cell Differentiation in Benign Tumors and Tumorlike Proliferation of Peripheral Nerves

An unusual, benign, spindle cell peripheral nerve sheath tumor (PNST) is reported that on ultra-structural examination was composed only of perineurial cells. The neoplastic cells showed positive immunoreactivity for S-100 protein and negative immunoreactivity for epithelial membrane antigen; this is not the expected immunophenotype of a perineurioma. Continued examination of benign PNSTs using electron microscopy and immunohistochemistry has the potential to reveal additional variations in the cellular composition and immunophenotype of these soft tissue tumors. PNSTs such as the one described will renew the debate about the cytogenesis of the perineurial cell and its role in PNSTs.     

Perineurioma of the Adrenal Gland

ABSTRACT

The authors report the first case of perineurioma of the adrenal gland. The tumor was composed of elongated wavy spindle cells focally arranged in a fascicular pattern. It was positive for epithelial membrane antigen (EMA) and claudin-1, and was negative for S-100 protein and glial fibrillary acidic protein (GFAP). Electron microscopy showed long, slender cytoplasmic processes coated by discontinuos basal lamina and presence of many pinocytotic vesicles.     

Malignant Melanoma of Soft Parts: An Ultrastructural Study of Four Cases

Samples from three clinically functional retroperitoneal paragangliomas were studied by light and electron microscopy. The tumors exhibited a Zellballen pattern histologically, and ultrastructurally all three neoplasms consisted of cells containing catecholamine granules. Prominent cytoplasmic crystalloids were present in all cases. The crystalloids were identified in routine histologic sections, demonstrated eosinophilia, and stained with periodic acid-Schiff, Giemsa, phloxine-tartrazine, and azan stains. Ultrastructurally the crystalloids were osmiophilic, often appeared as slender needles, were membrane bound, and demonstrated a periodicity of 9 nm. The crystalloids, unlike the catecholamine granules, were negative for catecholamine fluorescence. X-ray microanalysis, however, revealed the selective presence of chromium in both catecholamine granules and crystalloids.     

Plexiform Soft Tissue Tumor Composed Predominantly of Perineurial Fibroblasts (Perineurioma)

A 15-year-old girl presented with a small, indolent mass near the knee joint. Light microscopy revealed a peculiar myxoid plexiform tumor composed of cytologically bland cells. Interpretation of the initial biopsy material was controversial. Subsequent immunohistochemical studies revealed tumor cells to be strongly reactive for epithelial membrane antigen (EMA) and negative for S-100 protein. Ultrastructural studies revealed tumor cells with long, thin, bipolar cell processes and discontinuous basal laminae. They had no epithelial or histiocytoid features. Admixed among the tumor cells were Schwann cells, but they represented a rare and scattered component of the overall cell population. These features are most consistent with a so-called perineurioma and contrast with those of plexiform neurofibroma and traumatic neuroma (two lesions strongly positive for S-100 protein and showing a distinctive EMA immunoreactivity pattern with focal peripheral staining of neural bundles).     

Extracellular matrix in hepatoblastoma: an immunohistochemical investigation

Eleven hepatoblastomas of various subtypes and normal liver tissue were investigated with antibodies against collagen types I-VI, laminin, fibronectin and endothelial and macrophage-associated antigens. Epithelial hepatoblastoma cells, unlike non-neoplastic hepatocytes, exhibited intracellular immunoreactivity for various extracellular matrix proteins (depending on the subtype: laminin, fibronectin and collagen types III, IV and V). The intracellular expression of extracellular matrix proteins by the tumour cells increased from the fetal subtype, through the embryonal subtype, to the small cell subtype. The epithelial tumours exhibited sinusoid-like blood vessels in numbers that varied according to the subtype. These contained Kupffer cells and exhibited greater amounts of the basement membrane components collagen type IV and laminin in the perisinusoidal space than those in the normal liver. The small cell hepatoblastoma exhibited smaller numbers of sinusoids, pronounced intracellular expression of extracellular matrix proteins and large numbers of fibres immunoreactive for collagen type III. In the mixed hepatoblastomas, the extracellular matrix of the osteoid was most strongly immunoreactive for collagen type I and that of the spindle cell areas for collagen type III.     

Plexiform Soft Tissue Tumor Composed Predominantly of Perineurial Fibroblasts (Perineurioma)

A 15-year-old girl presented with a small, indolent mass near the knee joint. Light microscopy revealed a peculiar myxoid plexiform tumor composed of cytologically bland cells. Interpretation of the initial biopsy material was controversial. Subsequent immunohistochemical studies revealed tumor cells to be strongly reactive for epithelial membrane antigen (EMA) and negative for S-100 protein. Ultrastructural studies revealed tumor cells with long, thin, bipolar cell processes and discontinuous basal laminae. They had no epithelial or histiocytoid features. Admixed among the tumor cells were Schwann cells, but they represented a rare and scattered component of the overall cell population. These features are most consistent with a so-called perineurioma and contrast with those of plexiform neurofibroma and traumatic neuroma (two lesions strongly positive for S-100 protein and showing a distinctive EMA immunoreactivity pattern with focal peripheral staining of neural bundles).     

Low-grade malignant perineurioma of the paravertebral column, transforming into a high-grade malignancy

A demarcated 6 x 5 cm right paravertebral tumor at the level of T6 in a 39-year-old male was removed surgically. Histologically, the tumor consisted of monomorphous benign-looking, low-cellular spindle cells embedded in desmoplastic stroma. Ten years later, the tumor recurred locally with metastasis to systemic organs, including the occipital skin. Malignancy was histologically evident by the increased cellularity, cellular atypia and mitotic activity. The patient died of respiratory failure at the age of 49. Retrospectively reviewed, the primary lesion was low-grade fibrosarcoma-like spindle cell tumor, with secondary transformation into a highly malignant form. The differential diagnoses included sclerosing epithelioid fibrosarcoma, low-grade fibromyxoid sarcoma and malignant peripheral nerve sheath tumor. Immunohistochemically, the spindle cells in the primary and recurrent tumors consistently expressed epithelial membrane antigen, vimentin, type 4 collagen and laminin. The tumor cells in the present case showed a differentiation toward perineurial cells, which are normally positive for these immunohistochemical markers. Hence, the appropriate diagnostic term should be 'malignant perineurioma', a subtype of malignant peripheral nerve sheath tumor.     

Ovarian Sertoli-Leydig Cell Tumor with Rhabdomyosarcoma: An Ultrastructural Study

The clinical and light and electron microscopic findings of a moderately differentiated, virilizing, Sertoli-Leydig cell tumor (SLT) with pleomorphic rhabdomyosarcoma of the ovary are presented. The tumor recapitulates the primitive embryonal testis and rhab-domyogenesis, respectively. The natural history, including pathogenesis, of this peculiar and rare tumor is discussed in the light of the pertinent literature on SLT and ovarian rhabdomyosarcoma. It seems that when rhabdomyosarcoma is a significant or predominant component of SLT, as occurred in this case, the prognosis is poor and is that of rhabdomyosarcoma in general.     

Ovarian Sertoli-Leydig Cell Tumor with Rhabdomyosarcoma: An Ultrastructural Study

The clinical and light and electron microscopic findings of a moderately differentiated, virilizing, Sertoli-Leydig cell tumor (SLT) with pleomorphic rhabdomyosarcoma of the ovary are presented. The tumor recapitulates the primitive embryonal testis and rhab-domyogenesis, respectively. The natural history, including pathogenesis, of this peculiar and rare tumor is discussed in the light of the pertinent literature on SLT and ovarian rhabdomyosarcoma. It seems that when rhabdomyosarcoma is a significant or predominant component of SLT, as occurred in this case, the prognosis is poor and is that of rhabdomyosarcoma in general.     

B16黑色素瘤组织中上皮型钙黏附分子和S-100蛋白的表达及意义

目的:探讨B16黑色素瘤小鼠体内上皮型钙黏附分子与S-100蛋白的表达在肿瘤侵袭及转移过程中发挥的作用。方法:C57纯系小鼠分为12d和25d肿瘤组和正常对照组。肿瘤组将B16黑色素瘤细胞人工植入C57小鼠背部皮下,制荷瘤鼠模型,免疫组织化学法检测肿瘤病变中心区及交界区皮肤上皮型钙黏附分子和S-100的表达。结果:12d肿瘤组肿瘤组织中S-100蛋白表达的面密度和数密度明显增高,与正常对照组和25d肿瘤组比较差异有统计学意义;肿瘤组织中上皮型钙黏附分子表达的面密度和数密度较正常对照组明显降低。结论:上皮型钙黏附分子和S-100蛋白的异常表达在皮肤黑色素瘤的恶性进展过程中起重要作用,其表达程度可作为判断黑色素瘤恶性程度及预后的指标之一。     

Granular Cell Tumors on Unusual Anatomic Locations

Granular cell tumors (GCTs) are soft tissue tumors, which are thought to be derived from Schwann cells. Although most GCTs are reported to arise in tongue and oral cavity (30-50%), they can appear on any anatomic sites, even visceral organs. Herein, we report 5 cases of GCTs on unusual anatomic locations, such as palm, arm, thigh, finger, and vulvar area. Complete surgical excision is preferred treatment of choice to prevent recurrence. These cases emphasize that GCTs not involving oral cavity are more prevalent than expected, and the diagnosis should be histopathologically confirmed.     

Increased S-100 protein-immunoreactivity of Kupffer cells is associated with lymphohematological malignancy

The distribution of S-100 protein in normal tissue has been studied extensively. However, little is known about its expression in pathologic states. The aim of the present study was to investigate the expression of S100 protein in diseased human liver, especially in Kupffer cells. One hundred cases of autopsy livers originating from patients with various diseases were examined. Increased S-100-immunoreactivity of Kupffer cells was observed in six cases. Of the six cases, four were derived from a lymphohematologic malignancy, such as B cell lymphoma, B cell lymphoblastic leukemia, muitiple myeloma and chronic myelogenous leukemia with lymphoblastic crisis. Lymphohematologic malignancy accounted for 16 out of the 100 cases examined. Thus, increased S-100-positive Kupffer cells was significantly associated with lymphohematologic malignancy (P<0.01); 25% (4/16) in cases with lymphohematologic malignancy versus 2.4% (2/84) in the remaining cases. Moreover, some of these S-100-positive Kupffer cells were positive for S-100 β-subunit, which is not normally expressed by Kupffer cells. Although the reason for this increased S-100-immunoreactivity is speculative, the authors' hypothesis is that tumor cells may produce some factor(s) that induce the expression of S-100 protein in Kupffer cells.     

Benign schwannoma of the esophagus: Report of two cases with immunohistochemical and ultrastructural studies

Two cases of benign schwannoma of the esophagus are presented. The tumors were found in the thoracic esophagus of women of 56 and 64 years of age, respectively, who had complained of dysphagia and back pain. Tumorectomies were performed and the tumors were found to be located within the esophageal wall arising from the muscularis propria. The tumors were examined immunohistochemically and ultrastructurally. These tumors were identical in gross, histological and electron microscopic features. Grossly, the tumors showed yellowish-white cut surfaces without hemorrhage or necrosis. Microscopically, they were composed of spindle-shaped cells showing moderate variation in size and shape, and nuclear palisading. Lymphoid aggregates with germinal centers surrounded the tumors. Immunohistochemically, strong reactions for S-100 protein and neuron-specific enolase were observed in the cytoplasm of spindle cells, whereas reactions for muscle actin and desmin were negative. These findings, together with electron microscopic observations, supported the Schwann cell origin of these tumors.     

Cutaneous sclerosing Pacinian-like perineurioma

AIMS: The term perineurioma has been used to designate a variety of clinically and histologically different proliferations of perineurial cells based on immunohistochemical and/or ultrastructural characterization. There are two different groups of neoplasms derived from perineurial cells: extraneural or soft tissue perineuriomas, and intraneural perineuriomas. Recently, a sclerosing variant of cutaneous perineurioma has been described. METHODS AND RESULTS: We report a case of a cutaneous form of perineurioma, combining features of the intraneural and sclerosing varieties, as well as showing a Pacinian pattern of growth. In order to assess the neoplastic nature of the lesion, we performed fluorescence in-situ hybridization (FISH) analysis using a probe which maps to the chromosome band 22q11 and 22q13, allowing us to show deletion or loss of one chromosome 22 in the tumour cells. CONCLUSIONS: This case may be considered a new variant of perineurioma with Pacinian-like features, for which we propose the designation 'sclerosing Pacinian-like perineurioma'.     

Gastric Schwannoma

Schwannomas, also known as neurinomas or neurilemmomas, are generally benign, slow-growing neoplasms originating in any nerve that has a Schwann cell sheath. These neoplasms are rare among the spindle cell mesenchymal tumors of the gastrointestinal tract, but develop most commonly in the stomach representing 0.2% of all gastric tumors. We present the case of a 57-year-old female patient with a large schwannoma in the stomach that was palpable in the abdomen. She underwent subtotal gastrectomy under suspicion of gastrointestinal stromal tumor (GIST), but post-operative histopathological and immunohistochemical findings showed a fascicular arrangement of spindle cell with pallisading nuclei, and positive for S-100 protein with negative smooth muscle actin (SMA). These results confirmed schwannoma as the diagnosis.