Soft tissue myoepithelial tumors of the head and neck region are very rare, and only one case of soft tissue myoepithelial tumor occurring in the masticator space has been reported in the world literature. A case of soft tissue myoepithelial tumor with benign histomorphology, but with an invasive growth pattern, occurred in the masticator space of a 46-year- old male patient. Magnetic resonance imaging of paranasal sinus/nasopharynx revealed a well-defined, lobulated heterogeneous mass with high signal intensity and dense calcification in the masticator space between the left mandible ramus and pterygoid process. Grossly, the tumor was a well- circumscribed ovoid solid mass and consisted of yellowish gray glistening firm tissue. Histologically, the tumor showed a multinodular growth pattern and consisted of epithelioid cells in chondromyxoid stroma and of spindle-shaped to ovoid cells in the hyaline stroma. The tumor cells appeared bland, and no mitosis or necrosis was found within the tumor. The tumor focally invaded to adhered bone tissue. Immunohistochemically, the tumor cells were diffusely positive for epithelial membrane antigen, smooth muscle actin, but negative for other epithelial markers. Ultrastructurally, the cytoplasm of the tumor cells contained sparse microfilaments and subplasmalemmal densities. Attenuated desmosomes were commonly seen between the tumor cells.
Stomatognathic Diseases/*pathology ; Soft Tissue Neoplasms/*pathology/ultrastructure ; Myoepithelioma/*pathology/ultrastructure ; Middle Aged ; Microscopy, Electron ; Male ; Immunohistochemistry ; Humans

Spindle cell hemangioendothelioma is a rare vascular tumor which is presented with subcutaneous nodules and follows a benign indolent course but has a recurrent tendency, and is histologically resembling a cavernous hemangioma and Kaposi's sarcoma. We present a case of spindle cell hemangioendothelioma possessing clinical aggressiveness with painful bony erosion, histologic pleomorphism and mitoses. A 20-year-old man presented with a recurrent painful mass on the left ankle. The mass was dark brown and firm with irregular margins and measured 1.5 cm in diameter, which affected and eroded the underlying medial malleolus of the left tibia. Microscopically, the tumor was composed of cavernous endothelial-lined blood spaces and spindle cellular areas mimicking Kaposi's sarcoma. The spindle cells intermingled with plump epithelioid cells and showed a moderate degree of pleomorphism with occasional mitoses. Immunohistochemically, the spindle cells were focally positive for factor VIII-associated antigen and vimentin, and negative for S-100 protein, desmin, and epithelial membrane antigen.
Adult ; Bone and Bones/pathology ; Case Report ; Hemangioendothelioma/*diagnosis/pathology/ultrastructure ; Human ; Male ; Microscopy, Electron ; Soft Tissue Neoplasms/*diagnosis/pathology/ultrastructure

OBJECTIVETo study the clinicopathological, immunohistochemical and electron microscopic characteristics of pediatric rhabdomyosarcomas (RMS).

METHODSOne hundred and forty-five cases of pediatric rhabdomyosarcomas were studied by routine histological, immunohistochemical and electron microscopic studies.

RESULTSThere were 97 male and 48 female patients with ages ranging from 4 months to 13 years and a mean of 4.2 years. The follow-up period of 100 patients was from 1 year to 20 years with a mean of 5 years after diagnosis. All cases were subtyped into the following histological categories: embryonal RMS, botryoid RMS, spindle cell RMS, alveolar RMS and solid RMS. Histopathological subtypes, tumor site and tumor stage correlated significantly with the patients' 5 years survival. The best prognosis was observed in spindle cell and botryoid RMS. Embryonal RMS carried an intermediate prognosis. Patients with alveolar RMS and solid RMS had the worst prognosis. Tumors involving bladder, head and neck carried a favorable clinical outcome. Patients with tumors involving trunk extremities retroperitoneum and pelvis did poorly. Immunohistochemically, all cases were positive for Vimentin. The positive staining rates for desmin, SMA and myoglobin were 78%, 75% and 37%, respectively. All tumors were negative for NSE, CD99 and LCA. Electron microscopy study showed features of myofilament and sarcomere in 10 of 15 cases.

CONCLUSIONSRMS is the most common soft tissue sarcoma of childhood. Immunohistochemistry and electron microscopy are helpful in diagnosis and classification of RMS.

Adolescent ; Child ; Child, Preschool ; Female ; Follow-Up Studies ; Head and Neck Neoplasms ; pathology ; ultrastructure ; Humans ; Immunohistochemistry ; Infant ; Male ; Retrospective Studies ; Rhabdomyosarcoma ; classification ; pathology ; ultrastructure ; Soft Tissue Neoplasms ; classification ; pathology ; ultrastructure ; Urogenital Neoplasms ; metabolism ; pathology ; ultrastructure

BACKGROUNDPleomorphic hyalinizing angiectatic tumor (PHAT) of soft parts is a rare soft tissue tumor, which is generally considered low-grade. To distinguish the tumor from other soft tissue lesions, we analyzed the clinicopathologic and ultrastructural features, immunophenotypes, and flow cytometric DNA ploidy of PHAT in 9 cases.

METHODSPHAT specimens were collected from 9 patients with PHAT from 1990 to 2004. Each specimen was cut into pieces and stained with hematoxylin-eosin, phosphotungstic acid-hematoxylin, Prussian blue, and Masson trichrome, respectively. Immunohistochemical stains for vimentin, S-100 protein, CD34, CD31, CD99, VEGF, desmin, CD117, alpha-SMA, and MIB-1 were performed with the Envision system. Flow cytometry was used in four specimens, two of which were observed by electron microscopy.

RESULTSIn the 9 cases, the PHAT occurred at the lower extremity in 2 patients, inguinal in 2, waist in 1, forearm in 1, buttock in 1, foot in 1, and the chest wall in 1. All the lesions presented in the superficial subcutaneous tissues. Follow-up data were available in 7 of the patients, among whom 2 (28.6%) had recurrence after primary therapy. Microscopically, typical PHAT was characterized by sheet-like proliferation of spindle or pleomorphic cells and clusters of thin-walled hyalinized cstatic vessels. In some areas of the tumor, hemosiderin-laden spindle cells, numerous small single vessels, and myxoid extracellular matrix could be identified, indicating an "atypical PHAT". Mitotic figures were rare in all the cases. In 5 of the 9 patients (55.6%), the tumor was typical PHAT; and in the other 4 (44.4%), typical and atypical PHAT coexisted. Immunohistochemically, the neoplastic cells were positive for vimentin, CD34, CD99, and VEGF, but negative for S-100 protein, desmin, SMA, and CD31. In all the cases, the MIB-1 proliferative activity of the neoplastic cells was lower than 2%. Ultrastructural analysis did not reveal any evidence of specific differentiation. Aneuploidy was not detected by flow cytometry.

CONCLUSIONSHistologically, typical PHAT is characterized by spindle and pleomorphic cells associated with an angiectatic vasculature. The neoplastic cells often express vimentin and CD34, and may be positive for CD99 and VEGF. Ultrastructurally, the tumor usually has no specific differentiation. The low MIB-1 index and the absence of aneuploidy in PHAT indicate a non-malignancy. However, we consider the tumor as a borderline neoplasm because of its aggressive behaviour, and suggest wide local resection with tumor-free margin for the treatment of the disease.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Diagnosis, Differential ; Female ; Flow Cytometry ; Humans ; Hyalin ; Immunohistochemistry ; Male ; Middle Aged ; Prognosis ; Soft Tissue Neoplasms ; diagnosis ; pathology ; therapy ; ultrastructure

BACKGROUNDMelanotic schwannoma is a rare variant of schwannoma composed of melanin-producing cells with ultrastructural features of schwann cells. The description of the course of the tumors differs somewhat, but it is generally considered as a benign lesion. We investigated the clinicopathologic features, immunophenotypes, and ultrastructural features of 13 patients with nonpsammomatous melanotic schwannoma (NPMS).

METHODSTumor specimens of each patient were sectioned and stained with hematoxylin-eosin, Fontana-Masson, Prussian blue, and periodic acid-Schiff (PAS). Immunohistochemical markers such as S-100, Leu-7, HMB-45, Melan-A, CK, EMA, vimentin, GFAP, laminin, collagen IV and MIB-1 were detected with the Envision immunohistochemical staining method. Four of the cases were observed by electron microscopy.

RESULTSOf the 13 patients, 8 were male and 5 female, aged from 11 to 92 years (mean, 38.6 years). The tumor sites included the spinal nerve root (5 patients), cranial nerve (1), greater omentum (1), subcutaneous tissue (3), mesentery (1), bone (1) and mediastinum (1). Eleven patients were followed up for over 2 years, with a mean of 5.9 years. One patient (9.1%) with a primary tumor in the greater omentum developed another primary tumor of the same type in the subcutaneous tissue of the abdominal wall after the first operation. Local recurrence of the tumor was seen in 2 patients (18.2%). One patient (9.1%) showed the local recurrence and metastasis. Seven patients (63.6%) showed no evidence of the recurrence or metastasis. Grossly, all tumors were well-circumscribed and the gross findings were suggestive of melanin-containing tumors. The tumor was composed of spindled and epithelioid cells with abundant intracytoplasmic melanin pigments. Nuclei were round and contained delicate, evenly distributed chromatins as well as small, distinct nucleoli. In some areas, the nucleoli were large and prominent. Rare mitoses were seen in most lesions except the larger omentum lesion. The pigment was shown to be positive for the Fontana-Masson and negative for Prussian blue and PAS. Immunohistochemical staining for S-100, Leu-7, HMB-45, Melan-A, and vimentin were strongly positive. Linear immunoreactions of both laminin and collagen IV was detected in all patients. Ultrastructurally, numerous elongated tumor-cell processes, duplicated basement membrane and melanosomes were observed in all developmental stages.

CONCLUSIONSHistologically, melanotic schwannoma is a rare variant of schwannoma composed of melanin-producing cells with ultrastructural features of schwann cells. Distinguishing between this tumor and malignant melanoma is of paramount importance in planning of management. Immunohistochemically, combined use of laminin and collagen IV is valuable in distinguishing melanotic schwannoma from malignant melanoma. Wide local resection and additional radiotherapy should be advocated. Further studies including cytogenetic or molecular biology are still required to better delineate melanotic schwannoma from malignant melanoma. Appropriate long-term follow-up is needed for all melanotic schwannomas.

Adult ; Aged ; Aged, 80 and over ; Child ; Diagnosis, Differential ; Female ; Humans ; Immunohistochemistry ; Male ; Microscopy, Electron ; Middle Aged ; Neurilemmoma ; chemistry ; mortality ; pathology ; ultrastructure ; Prognosis ; Soft Tissue Neoplasms ; chemistry ; mortality ; pathology ; ultrastructure