[Pseudoangiomatous spindle cell lipoma: about six cases]. / Le lipome à cellules fusiformes pseudoangiomateux : à propos de six cas.

AIMS: Pseudoangiomatous spindle cell lipoma (PASCL) is a rare variant of spindle cell lipoma. Nine cases have been previously described in the literature. In this retrospective study, we report six cases reviewed in the department of pathology at the Bergonié Institute between 01/01/1987 and 31/12/2009. METHODS: Clinical and histological data were reviewed. A standard histological study was realized and immunochemistry was performed with smooth muscle actin (SMA), desmin, epithelial membran antigen (EMA), S 100 protein, CD34, CD31, MDM2, CDK4. RESULTS: All patients were male and median age was 52. Median size was 3cm. We report four atypical locations: cheek, finger, elbow and jaw. DISCUSSION: In our series, the frequency of PASCL was 1,25% of all spindle cell lipomas. Histological and immunohistochemical aspects are identical to those observed in the literature. CONCLUSION: The pattern of PASCL is typical, particularly with the positivity of CD34, which is stronly suggestive of diagnosis.

Melanotic neuroectodermal tumor of infancy presenting in the subcutaneous soft tissue of the thigh.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare and diagnostically challenging neoplasm typically presenting in the bones of the maxilla, skull, or mandible. Only 6 of approximately 357 reported cases have involved the subcutis. We describe a case of MNTI presenting as a palpable, subcutaneous, thigh mass in a 5-month-old girl. By ultrasound, the mass was round with well-defined borders, minimal vascularity, and heterogeneous echogenicity. Microscopically, the tumor consisted of nested foci of primitive-appearing small round blue cells with an increased nuclear to cytoplasmic ratio, stippled chromatin, and occasional mitotic figures. A larger and more epithelioid second cell population exhibited eosinophilic cytoplasm and sparse pigmented granules. The background stroma was fibrous and densely sclerotic. The differential diagnosis of soft tissue MNTI can include melanoma, neuroblastoma, rhabdomyosarcoma, desmoplastic small round cell tumor, and other pediatric "small round cell" neoplasms. The tumor had the characteristic immunophenotype of MNTI: cytokeratin+, HMB-45+, neuron-specific enolase+, and synaptophysin+. MNTI should be considered in the differential diagnosis of pigmented soft tissue lesions in children. Our patient remains disease-free 40 months after excision, although these tumors can locally recur (10%-20%) and rarely metastasize.

Reticular perineurioma: a distinctive variant of soft tissue perineurioma.

Soft tissue perineurioma is a relatively recently characterized, uncommon tumor composed of perineurial cells exhibiting immunoreactivity for epithelial membrane antigen (EMA). These lesions occur preferentially in adults and may arise in a wide variety of anatomic sites. We report the clinicopathologic, immunohistochemical, and ultrastructural features of six cases of a poorly recognized morphologic variant of soft tissue perineurioma, characterized by a highly distinctive reticular growth pattern. Four of the patients were women, two were men (age range, 34-61 yrs; median, 43 yrs). Four of the cases arose in the subcutis of the upper extremity; three were located distally (thumb, finger, palm), whereas one was situated more proximally near the elbow region. One case each was located in the gingiva and subcutaneous tissue of the inguinal region, respectively. In those cases in which clinical information was available (n = 5), the lesions were asymptomatic and had been present from 4 months to 10 years before resection. Tumor size ranged from 1.5 cm to 10 cm (median size, 4.25 cm). Microscopically the lesions demonstrated a predominantly lace-like or reticular growth pattern composed of anastomosing cords of fusiform cells with bipolar cytoplasmic processes and palely eosinophilic cytoplasm. Nuclei were centrally placed, ovoid to fusiform in shape, and no mitoses were seen. Transition to more cellular areas was focally present in all cases. The stroma was variably collagenous to myxoid. Immunohistochemically all six cases stained positively for EMA but not for S-100 protein. Two cases demonstrated focal positive cytoplasmic staining for cytokeratin, whereas one case was focally desmin positive. Ultrastructural examination of two tumors showed typical features of perineurial cells. Follow up (available in only two cases) showed no evidence of recurrence. Reticular perineurioma of soft tissue represents an unusual morphologic variant within the perineurioma group, which should be distinguished from myoepithelial tumors, extraskeletal myxoid chondrosarcoma, and myxoid synovial sarcoma.

S100, alpha-smooth muscle actin and cytokeratin 19 immunohistochemistry in odontogenic and soft tissue myxomas.

AIMS: To compare the expression of S100 protein, alpha-smooth muscle actin (alpha-SMA) and keratin 19 in odontogenic myxomas and non-odontogenic myxoid lesions. METHODS: Formalin fixed, paraffin wax embedded tissue from seven odontogenic myxomas, three soft tissue myxomas, six hyperplastic myxoid dental follicles, two intramuscular myxomas, 12 cardiac myxomas, and seven normal dental follicles were examined immunocytochemically for S100 protein, alpha-SMA and cytokeratin 19 using the Streptavidin-biotin method. RESULTS: A minority of odontogenic myxomas (three of seven) were positive for S100 and the staining was of moderate intensity and in all myxofibroblasts. Soft tissue myxomas, normal dental follicles, intramuscular myxomas, and most enlarged myxoid follicles were negative. In the cardiac myxomas the cells forming cords and islands were positive in approximately half (seven of 12), but the dispersed stellate myxoblasts were positive in only two cases. A population of cells in all the odontogenic myxomas and hyperplastic dental follicles contained alpha-SMA, but such cells were sparse in cardiac myxomas and present in only four cases. Cytokeratin 19 was present in odontogenic epithelium of odontogenic myxoma and follicles. CONCLUSIONS: A minority of odontogenic myxomas, but not other oral myxoid lesions, may express S100 protein and this could cause difficulty distinguishing myxoma from myxoid nerve sheath tumours. Sparse myofibroblastic cells occurred in all types of myxoma tested. The epithelium sometimes found within jaw myxomas expresses cytokeratin 19 and this is consistent with an odontogenic origin.

Identification of syt-ssx fusion transcripts in both epithelial and spindle cell components of biphasic synovial sarcoma in small tissue samples isolated by membrane-based laser microdissection.

In order to confirm the presence of SYT-SSX fusion gene in epithelial and spindle cell components of synovial sarcoma, we performed a nested reverse transcriptase-polymerase chain reaction (RT-PCR) using microbeam microdissection of membrane-mounted native tissue (MOMeNT) technique applied on formalin-fixed, paraffin-embedded tumor specimens from two biphasic synovial sarcomas and a control tissue of adamantinoma. Small targeted portions of either an epithelial or spindle cell component of the tumor tissue were microdissected together with the supporter membrane, by using an ultraviolet (337-nm) pulsed laser microbeam coupled into a robot-stage microscope with infinity optics. The SYT-SSX fusion transcript was detected in epithelial and spindle cell components of both biphasic synovial sarcomas, but not in the control tissue. Southern blot analysis also confirmed that the detected messages were derived from the SYT-SSX fusion gene. In conclusion, the microbeam MOMeNT is a useful method for isolating selected small portions from tissue sections. The SYT-SSX fusion gene is present in both cellular components of biphasic synovial sarcoma and is involved in oncogenesis of the synovial sarcoma rather than in morphologic epithelial differentiation. Therefore, in spite of the variable proportions of each component, our results confirm that the synovial sarcoma is of monoclonal origin.

Tumors of the soft tissues composed of large eosinophilic cells.

Soft tissue neoplasms composed of large eosinophilic cells include benign and malignant tumors with different degrees of biological aggressiveness. The main histotypes discussed in this review are the heterogeneous group of benign and malignant granular cell tumors with neural and non-neural differentiation, alveolar soft part sarcomas, rhabdomyomas, and rhabdomyosarcomas. The salient anatomic, clinical, morphological, and immunophenotypic features in differential diagnosis with metastatic melanomas, carcinomas, and paragangliomas are discussed separately for each histotype.

Comparison of tetrachromic VOF stain to other histochemical staining techniques for characterizing stromal soft and hard tissue components.

The components of hard tissues including dentin, enamel, cementum, bone and other calcified deposits, and mature and immature collagen pose problems for identification in routine hematoxylin and eosin (H & E) stained sections. Use of combinations of stains can demonstrate the components of hard tissues and soft tissues distinctly. We assessed the efficacy of the Verde Luz-orange G-acid fuchsin (VOF) stain for differentiating hard and soft connective tissues and compared results with other histochemical staining techniques. Eighty tissue sections comprising developing tooth (30), ossifying fibroma (30) and miscellaneous pathologies (20) expected to contain varying types of calcified tissues were stained with H & E, VOF, and Masson's trichrome (MT). In developing tooth, VOF demonstrated better differentiation of hard tissues, while it was comparable to MT for ossifying fibroma and miscellaneous pathologies. The intensity of staining was greater with VOF than with the other stains studied. VOF stains hard tissue components distinctly and gives good contrast with the surrounding connective tissue. VOF is comparable to MT, but has added advantages including single step staining, rapid and easy procedures, and it distinguishes the maturity of the tissues.

Soft tissue amyloidoma of the extremities: report of a case and review of the literature.

Amyloidoma (tumoral amyloidosis) is defined as a solitary localized tumorlike deposit of amyloid, in the absence of systemic amyloidosis. Amyloidoma is the least common presentation of tissue amyloid deposition and may be of AL-type or AA-type. It has been reported in many anatomic sites including the respiratory, genitourinary, and gastrointestinal tracts, as well as internal viscera, the central nervous system, skin, breast, and soft tissues. Amyloidoma of soft tissues is extremely rare and occurs mainly in the mediastinum and abdomen. Soft tissue amyloidoma of the extremities is even more uncommon and, when strictly defined, only 11 such cases are reported in the English language to date. Most have been of AA-type and have occurred on the leg. Some have been associated with local trauma, surgery, infection, or peripheral vascular disease, and a few patients have been diabetic. We report the case of a soft tissue amyloidoma on the leg of an 85-year-old woman. Clinically, it was a subcutaneous nodule on the left shin, of approximately 4 years duration. Traumatic fat necrosis was suspected. On excision a firm gray/tan, lobulated, soft tissue mass, measuring 2.3 cm in greatest dimension, was observed. At the microscopic level, it was seen to consist mainly of amyloid, associated with a giant cell granulomatous reaction, a patchy lymphocytic infiltrate, and focal microcalcification. The features were those of a soft tissue amyloidoma of the extremity. Persistence of congophilia after pretreatment with permanganate in this case suggested the presence of AL amyloid.

Solitary fibrous tumor in the mental region.

Solitary fibrous tumor (SFT) is a rare, benign, soft tissue tumor that most commonly occurs in the pleura; however, it has recently been described in other sites of the body. To date, eight examples of oral SFT have been reported. This paper is a description of the first case of an SFT occurring as a soft tissue tumor in the mental region. Histologically, the tumor was composed predominantly of rather uniform spindle-shaped fibroblastic cells arranged in vague fascicles or in a haphazard fashion, intermingled with abundant collagen fibers. Immunohistochemically, the tumor cells were positive for CD34 and vimentin, and weakly positive for muscle actin and alpha-smooth muscle actin. The diagnosis of SFT may be difficult as this tumor shares a number of histological features with other soft tissue tumors. Awareness of its occurrence in the oral cavity is important so that confusion with other spindle cell neoplasms can be avoided.

Immunohistochemical evaluation of oral myxoid lesions.

Oral examples of neurothekeomas (nerve sheath myxomas), soft tissue myxomas, and focal mucinous and odontogenic myxomas were examined for selected markers. With the use of avidin-biotin complex staining procedures, these specimens of lesions were stained with antibodies to S-100 protein, neurospecific enolase, neurofilaments, desmin, and vimentin. Our results show that the use of immunohistochemical markers for these neural antigens can aid in distinguishing nerve sheath myxomas from other oral myxoid lesions.