Alveolar Soft-Part Sarcoma of the Tongue.

Alveolar soft-part sarcoma is a rare neoplasm of unknown histogenesis that accounts for less than 1% of all soft-tissue sarcomas. The tumor is highly vascularized with small vascular spaces separating nests of cells, and from cytogenetic point of view, is characterized by chromosome rearrangement der(17)t(X:17)(p11:q25) that results in the ASPL-TFE3 translocation. It can occur at any age, but it is most common between 15 and 35 years of age. The prognosis is poor, despite the relatively slow growth of the tumor. We present here an atypical case of alveolar soft-part sarcoma in which the age of the patient, the location, and the histopathologic characteristics of the lesion represented a diagnostic challenge.

Alveolar soft part sarcoma: clinical, histopathological, molecular, and ultrastructural aspects.

Alveolar soft part sarcoma (ASPS) is a rare soft tissue tumor occurring mainly in the adolescents and young adults. Multimodality treatment has not been effective, and excision remains the mainstay of treatment. Histopathologically, it varies little from case to case. It is composed of organoid aggregates of large polygonal cells with vesicular nuclei and abundant granular, eosinophilic cytoplasm, separated by delicate vascular channels. The line of differentiation of this unique tumor is yet undetermined, although recent advances have led to a better understanding of the genetic events underlying the pathogenesis of this tumor. The histopathological, ultrastructural, immunohistochemical, and genetic aspects of ASPS are discussed.

Malignant perivascular epithelioid cell tumor of the oropharynx with strong TFE3 expression mimicking alveolar soft part sarcoma: a case report and review of the literature.

Perivascular epithelioid cell tumors (PEComas) in the head and neck region are rare, with 26 cases described in literature. These distinct mesenchymal tumors normally express both myoid and melanocytic markers. We here report an interesting and challenging case of malignant PEComa that showed transcription factor E3 (TFE3) protein expression and rearrangement, paucity of muscle and melanocytic marker expression, and morphologically mimicked alveolar soft part sarcoma. Awareness of this morphologic pitfall and recognition of TFE3 gene-rearranged PEComa, as a distinct subtype of PEComa, is essential to avoid misdiagnosis.

Alveolar Soft Part Sarcoma of the Female Genital Tract: A Morphologic, Immunohistochemical, and Molecular Cytogenetic Study of 10 Cases With Emphasis on its Distinction From Morphologic Mimics.

Alveolar soft part sarcoma (ASPS) is a morphologically distinctive neoplasm of unknown differentiation that bears a characteristic gene fusion involving ASPSCR1 and TFE3. ASPS can occur in the female genital tract, but is rare. Eleven cases with an initial diagnosis of ASPS at female genital tract sites were evaluated for their morphologic features and immunoprofile using a panel of antibodies (TFE3, HMB45, melan-A, smooth muscle actin, desmin, and h-Caldesmon). In addition, the presence of TFE3 rearrangement and subsequent ASPSCR1-TFE3 fusion were determined by fluorescence in situ hybridization. Ten tumors retained their classification as ASPS based on their morphologic appearance, immunohistochemical profile, and demonstration of ASPSCR1-TFE3 fusion. The remaining case was reclassified as conventional-type PEComa due to its pattern of HMB45, melan-A, and desmin positivity as well as absence of TFE3 rearrangement. Sites of the 10 ASPS were uterine corpus (3), cervix (2), uterus not further specified (2), vagina (2), and vulva (1). The age of the patients ranged from 15 to 68 years (mean 34 y, median 32 y). The tumors demonstrated a spectrum of morphologic features, but all had a consistent immunophenotype of strong TFE3 nuclear expression and lack of muscle (smooth muscle actin, desmin, h-Caldesmon) and melanocytic (melan-A, HMB45) markers, except focal positivity for HMB45 in 1. Follow-up was available for 4 patients ranging from 1 to 35 months (mean 15 mo, median 25 mo) and they were alive and had no evidence of recurrence or metastasis at last follow-up. Distinguishing ASPS from its morphologic mimics, particularly PEComa, is important due to increasingly efficacious targeted agents such as MET-selective and VEGF signaling inhibitors in the former and mTOR inhibition therapy in the latter.

Cytogenetic abnormalities of alveolar soft-part sarcomas using interphase fluorescent in situ hybridization: trisomy for chromosome 7 and monosomy for chromosomes 8 and 18 seem to be characteristic of the tumor.

Four alveolar soft-part sarcomas were investigated by means of standard immunohistochemistry and interphase cytogenetics to further characterize the immunophenotype and proliferative activity of this tumor. The main goal of this study was to explore the chromosomal changes of this rare soft-tissue sarcoma. One epithelial (KLI), three neurogenic [neuron specific enolase (NSE), PGP 9.5, and S100], and five myogenic (desmin, myoglobin, alpha-smooth mnuscle actin, alpha-sarcomeric actin, and MyoD1) markers were used for the immunophenotypical analysis. Proliferative activity was assessed using the Ki67 index. Twelve (peri)centromeric (1, 3, 4, 6, 7, 8, 10, 12, 15, 17, 18, and X) and one telomeric (17q25-qtel.) chromosomal probes were used for interphase cytogenetic analysis. Three of the cases showed cytoplasmic desmin and/or myoglobin, and one showed smooth muscle actin positivity. All of the four tumors had granular, cytoplasmic, possibly nonspecific MyoD1 and sarcomeric actin positivity. Two of the tumors were positive for vimentin, four gave focal and weak staining with neurogenic markers (four of four NSE, one of four S100, and four of four PGP 9.5), but none of them was positive with KLI. Alveolar soft-part sarcomas may show myogenic immunophenotype in a number of cases, which supports myogenic differentiation. Fluorescent in situ hybridization using alpha satellite chromosomal probes revealed significant alterations in all of the cases. Most frequent and repeated numerical changes, which seem to be characteristic of the neoplasm and may play an important part in its pathogenesis and/or progression, were trisomy 7, monosomy 8 and monosomy 18.

Alveolar soft part sarcoma of the uterine corpus. Report of two cases and review of the literature.

Alveolar soft-part sarcoma (ASPS) is a rare tumor of uncertain histogenesis, mainly localized in the extremities and less frequently found in the head, neck and trunk. The present report describes two cases of ASPS localized in the uterus. In general, this entity is very rarely encountered in the female genital tract. Including the two cases presented here, 27 patients have been described in the literature. Whereas the prognosis for ASPS in soft tissues is usually poor (most of the patients died of lung metastases), those localized in the female genital tract are associated with a much better survival. This could be explained by the fact that their diameter seldom exceeds 5 cm, the size which is regarded as being the critical prognostic limit. Histologically, both tumors showed the same characteristics as known for ASPS in other localizations: organoid or nest-like arrangement of tumor cells; rounded or polygonal cells with cytoplasm of varying density; thin-walled, sinusoidal vascular spaces between tumor cell nests. Immunohistochemically, we found positivity for desmin and, to a lesser extent, for vimentin. Cytokeratin was negative, which is important in differential diagnosis to other rare uterine neoplasias like clear cell (mesonephroid) adenocarcinomas or metastases.

Primary alveolar soft part sarcoma of the stomach: a case report and review.

Alveolar soft part sarcoma (ASPS) is a rare tumor typically located in skeletal muscles and muscolofascial planes. Isolated cases of ASPS have been described as arising in the viscera. We report a mesenchymal tumor of the stomach in a 54-year-old Italian woman without evidence of primary neoplasm elsewhere ten years following the initial diagnosis. The histologic, histochemical, immunohistochemical, and electron microscopic findings were all consistent with the diagnosis of ASPS and allowed differentiating it from morphologically similar and more common tumors, such as metastatic renal cell carcinoma and paraganglioma. The patient is alive and well ten years following the initial presentation.

Immunohistochemical profile of myogenin and MyoD1 does not support skeletal muscle lineage in alveolar soft part sarcoma.

BACKGROUND: The histogenesis of alveolar soft part sarcoma remains elusive. Myogenic origin is favored, although conflicting data on immunohistochemical demonstration of muscle-associated markers exist. Myogenin and MyoD1, transcription factors of the myogenic determination family, have crucial roles in commitment and differentiation of mesenchymal progenitor cells to myogenic lineage and in maintenance of skeletal muscle phenotype. Their immunohistochemical detection is specific in characterization of rhabdomyosarcoma. METHODS: Antibodies for myogenin, MyoD1, desmin, and muscle-specific actin were employed on a large series of cases (n = 19) of formalin-fixed, paraffin-embedded alveolar soft part sarcoma. RESULTS: Minimal scattered nuclear staining was seen with myogenin. All cases had pronounced, nonspecific granular cytoplasmic immunostaining with MyoD1; nuclei were negative. All tumors were negative for desmin and muscle-specific actin. Ultrastructural study in 10 cases failed to reveal features of skeletal muscle differentiation. CONCLUSIONS: Cytoplasmic staining with MyoD1 in alveolar soft part sarcoma may correspond to cross-reactivity with an undetermined cytoplasmic antigen. The lack of immunostaining with myogenin, MyoD1, desmin, and muscle-specific actin provides evidence against a myogenic origin for alveolar soft part sarcoma.

Alveolar soft-part sarcoma: a new type of rhabdomyosarcoma?

Alveolar soft part sarcoma (ASPS) was described as a distinct entity in 1952. ASPS mainly affects young adults, with a slight prevalence of female patients. It arises in the extremities, trunk, and head and neck region. Metastases are frequent and are mainly localized to lungs, brain, and bone. Local recurrences are rare if the primary tumor is completely excised. Adjuvant chemotherapy or radiotherapy are not useful. Death eventually supervenes, after several years, in most of the patients. Histogenesis and differentiation of ASPS, since its first description, have remained a matter of controversy. Many hypotheses have been taken into consideration, among which neural and muscular differentiation are the most plausible. The finding that intracytoplasmic crystals, present in most of the cases, are composed of actin, and the immunocytochemical localization in ASPS of several muscular markers, such as actin (skeletal and smooth muscle actin), desmin, and MyoD1 are all features that point towards skeletal muscle differentiation.

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.

[Alveolar sarcoma. Report of a case]. / Sarcome alvéolaire du poumon. A propos d'une observation.

Alveolar soft part sarcoma occurs mostly in the deep soft tissues. An unusual case of primary pulmonary alveolar soft part sarcoma is reported. A 39-year-old woman presented with thoracic pain revealing the tumor. The left lower lobe was surgically resected. The microscopic features of this tumor, including characteristic alveolar pattern and the PAS-positive crystals were typical of alveolar soft part sarcoma. Immunohistochemically, granular cytoplasmic reactivities were observed with antibodies against vimentin, myoglobin, methionine-enkephalin, S100 protein and neuron-specific-enolase. Electron microscopic study demonstrated numerous crystallized structures in the tumor cell cytoplasm. This is the third case of pulmonary alveolar soft part sarcoma, one arising from the pulmonary vein. The histogenesis of alveolar soft part sarcoma is still debated. Our case does not allow distinction between myogenic or neural origin of this tumor.

Alveolar soft part sarcoma and granular cell tumor: an immunohistochemical comparison study.

Although the histologic features of alveolar soft part sarcoma and granular cell tumor are typically distinctive, occasional cases show a significant morphologic overlap. Differentiating these entities is crucial because granular cell tumor is almost always benign and alveolar soft part sarcoma is invariably malignant. We evaluated a panel of immunohistochemical stains (S-100 protein, inhibin, SOX10, nestin, calretinin, and TFE3) in 13 alveolar soft part sarcomas and 11 granular cell tumors. Tissue sections were also stained by the periodic acid-Schiff method after diastase digestion (PAS-D) and evaluated for coarse cytoplasmic granularity or crystalline cytoplasmic inclusions. S-100 protein, inhibin, SOX10, and nestin each distinguished granular cell tumor and alveolar soft part sarcoma with 100% sensitivity and specificity. PAS-D staining also distinguished cases with 100% accuracy, as granular cell tumor consistently demonstrated coarsely granular, PAS-D-positive cytoplasm and alveolar soft part sarcoma showed only focal intracytoplasmic crystalline inclusions. Although all granular cell tumors were calretinin positive, so were 46% of alveolar soft part sarcomas. TFE3 was positive in 91% of granular cell tumors and all alveolar soft part sarcomas. Together with PAS-D, immunohistochemical stains for S-100 protein, inhibin, SOX10, and nestin accurately identify alveolar soft part sarcoma and granular cell tumor. Although TFE3 has been reported as a relatively specific marker for alveolar soft part sarcoma, it should be recalled that it is also expressed in most granular cell tumors.

Alveolar soft part sarcoma of the tongue: report of an unusual pattern in a child.

A case of an unusual, primary alveolar soft part sarcoma of the tongue in a 3-year-old boy is presented. Alveolar soft part sarcoma is a rare malignant tumor that presents more frequently in the head and neck region of infants and children. To date, only six cases of lingual alveolar soft part sarcoma presenting in the first decade of life have been reported in the English literature. The patient has undergone surgical resection without adjuvant chemotherapy or radiation. Thus far, the patient does not manifest persistent or recurrent disease.

Does alveolar soft-part sarcoma exhibit skeletal muscle differentiation? An immunocytochemical and biochemical study of myogenic regulatory protein expression.

There has been persistent controversy regarding the nature of cell differentiation in alveolar soft-part sarcoma (ASPS) since its first description in 1952. Some studies suggest that ASPS might represent an unusual variant of skeletal muscle tumor. Given the availability of new monoclonal antibodies to probe for skeletal muscle differentiation and the rapid advance in immunocytochemical techniques for deparaffinized, formalin-fixed tissue sections, we wished to test the proposed hypothesis that ASPS might represent a new type of rhabdomyosarcoma. Twelve archival samples of ASPS were retrieved, and we investigated the expression of two myogenic regulatory proteins, MyoD1 and myogenin, as well as other muscle-associated proteins, using sensitive immunocytochemical techniques. Despite the presence of desmin immunostaining in six ASPSs, no tumors were positive for either muscle actin or myoglobin. Most importantly, no specimen showed nuclear expression of MyoD1 or myogenin. In 11 tumors, however, there was considerable granular immunostaining in the tumor cell cytoplasm with the anti-MyoD1 monoclonal antibody 5.8A, a phenomenon observed in various nonmuscle normal and neoplastic tissues with this antibody. To analyze the exact nature of immunostaining of MyoD1 and desmin in ASPS, biochemical analyses using available fresh frozen tumor tissue were performed. Although a 53-kDa band was noted with antidesmin antibody on Western blot analysis, no specific protein band that corresponds to the 45-kDa MyoD1 was detected with antibody 5.8A. These results confirm the presence of desmin in ASPS but argue against authentic expression of MyoD1. They also suggest that the cytoplasmic immunostaining observed with anti-MyoD1 antibody 5.8A most likely represents a nonspecific cross-reaction with an unknown cytoplasmic antigen. Considering the master role that MyoD1 and myogenin play in skeletal muscle commitment and differentiation and the lack of expression of these two proteins in ASPS as determined immunocytochemically and biochemically, we think that the histogenesis of ASPS remains unknown.

Immunohistochemical examination of an orbital alveolar soft part sarcoma.

BACKGROUND: A 32 year-old male patient had a 6-week history of left-sided proptosis. Computer tomography revealed a 16x15x15 mm smooth and well-defined mass between the optic nerve and the medial and superior rectus muscles in the left orbit. METHODS: The tumour was excised via a cranio-medial orbitotomy approach. RESULTS: Histopathological examination, immunohistochemistry and electron microscopy findings were consistent with an alveolar soft part sarcoma. Immunohistochemical staining showed positive immunoreactivity for neuronespecific enolase, vimentin, p53 (30%), p21 (10%) and cyclin D1 (20%), and negative immunoreactivity for CD45, cytokeratins, S-100 protein, glial fibrillary acidic protein, synaptophysin, chromogranin, calcitonin, serotonin, thyreoglobulin, desmin, myosin, actin, HMB-45, pRB, p16 and BCL-2. The growth fraction of the tumour cells was 3%. At examination 4 years after surgical excision, there was no evidence of local recurrence or for metastases. CONCLUSION: Alveolar soft part sarcoma of the orbit is a rare malignant tumour best controlled by surgery. The unpredictable behaviour of these neoplasms, however, indicates the need for long-term follow-up.

Primary alveolar soft part sarcoma of bone.

AIMS: Alveolar soft part sarcoma is a distinct, rare soft tissue tumour occurring primarily within the skeletal muscles or musculofascial planes in young adults. Primary involvement of bone is extremely rare. We report on six patients with alveolar soft part sarcoma occurring primarily in bone. METHODS AND RESULTS: Thorough clinical and radiographic examinations were done to rule out any other primary site. The patients were four women and two men aged 17-35 years (mean, 24.5 years). The primary site of the tumour was the femur in three patients, the ilium in one and the fibula in two. In one of the patients with fibular involvement, the tibia was also involved by direct extension. Of the long bone lesions, three were centred in the metaphysis and one in the diaphysis. Radiographically, all of the lesions demonstrated an osteolytic pattern of bone destruction with ill-defined margins and a wide zone of transition between the lesion and adjacent normal bone. Microscopically, all tumours showed the typical histological pattern of alveolar soft part sarcoma. Diastase-resistant, periodic acid-Schiff-positive crystalline structures were identified within the cytoplasm and confirmed ultrastructurally. Immunohistochemically, a keratin stain was negative in all cases; there was positive staining for MyoD1 in the cytoplasm but not the nuclei. Distant metastasis developed in four patients; one died. CONCLUSION: Alveolar soft part sarcoma arising in bone is extraordinarily rare but should be considered in the differential diagnosis of metastatic hypernephroma in a young patient.