Molecular characterization of epithelioid haemangioendotheliomas identifies novel WWTR1-CAMTA1 fusion variants.

AIMS: Epithelioid haemangioendothelioma (EHE) is a malignant vascular neoplasm. Subsets have been characterized previously by translocations resulting in either WWTR1-CAMTA1 or YAP1-TFE3 fusion. We sought to develop molecular and immunohistochemical (IHC) assays to aid in the diagnosis and characterization of EHE. METHODS AND RESULTS: Fifty-two formalin-fixed, paraffin-embedded (FFPE) cases diagnosed between 2002 and 2014 were retrieved from the pathology files of our institutions. Reverse transcription-polymerase chain reaction (RT-PCR) assays were optimized to detect WWTR1-CAMTA1 and YAP1-TFE3 fusion transcripts in FFPE tissue and transcription factor E3 (TFE3) protein accumulation was examined by immunohistochemistry (IHC). RNA was extracted from 33 adequate samples, with more recent cases providing a greater yield of high quality RNA. Fourteen of 18 informative cases were positive for WWTR1-CAMTA1 fusion transcripts, four of which showed higher-grade cytological features termed by some as 'malignant EHE'. Novel in-frame fusion transcripts were identified in four cases by direct sequencing. IHC revealed variable nuclear TFE3 staining in six of 17 cases; three with patchy staining showed WWTR1-CAMTA1 fusion. One of 18 informative cases was positive for YAP1-TFE3 fusion and showed strong nuclear TFE3 staining by IHC. CONCLUSIONS: This study confirms the high incidence of WWTR1-CAMTA1 and YAP1-TFE3 rearrangements in EHE and indicates that the staining pattern for TFE3 IHC is critical for specificity.

Oral alveolar soft part sarcoma in childhood and adolescence: report of two cases and review of literature.

Alveolar soft part sarcoma (ASPS) constitutes a rare soft tissue malignant neoplasm comprising less than 1 % of all soft tissue sarcomas. ASPS demonstrates a strong predilection for adolescents and young adults, with a female predominance reported. The head and neck region is the most commonly affected region in pediatric patients with the tongue and orbit affected most commonly. Herein we present the clinical, radiographic, histopathologic, immunohistochemical and molecular features of two examples of ASPS affecting the oral cavity of 4 and 13 year-old boys, along with a focused review of the literature on intraoral ASPS in pediatric patients.

Deletion of TAK1 in the myeloid lineage results in the spontaneous development of myelomonocytic leukemia in mice.

Previous studies of the conditional ablation of TGF-ß activated kinase 1 (TAK1) in mice indicate that TAK1 has an obligatory role in the survival and/or development of hematopoietic stem cells, B cells, T cells, hepatocytes, intestinal epithelial cells, keratinocytes, and various tissues, primarily because of these cells' increased apoptotic sensitivity, and have implicated TAK1 as a critical regulator of the NF-κB and stress kinase pathways and thus a key intermediary in cellular survival. Contrary to this understanding of TAK1's role, we report a mouse model in which TAK1 deletion in the myeloid compartment that evoked a clonal myelomonocytic cell expansion, splenomegaly, multi-organ infiltration, genomic instability, and aggressive, fatal myelomonocytic leukemia. Unlike in previous reports, simultaneous deletion of TNF receptor 1 (TNFR1) failed to rescue this severe phenotype. We found that the features of the disease in our mouse model resemble those of human chronic myelomonocytic leukemia (CMML) in its transformation to acute myeloid leukemia (AML). Consequently, we found TAK1 deletion in 13 of 30 AML patients (43%), thus providing direct genetic evidence of TAK1's role in leukemogenesis.

Primary intrathoracic dermatofibrosarcoma protuberans.

Dermatofibrosarcoma protuberans (DFSP) is defined as a low-grade sarcoma derived from an uncertain cell of origin in the reticular dermis. We report a fibrosarcomatous variant of DFSP (FS-DFSP) that arose primarily in the deep thoracic soft tissue. The patient was a 9-year-old girl who presented with dyspnea and low-grade fevers without a clinically detectable mass or a history of skin lesion. Imaging studies revealed a 10-cm mass entirely confined within the thoracic cavity. Three years after a marginal excision with adjuvant chemotherapy and radiotherapy, the tumor recurred in the paraspinal region. Histologically, the primary and recurrent tumors comprised a high-grade spindle cell sarcoma, with a small component of storiform, low-grade, CD34-positive spindle cells, classic for an ordinary DFSP. The diagnosis of FS-DFSP was confirmed molecularly by the demonstration of a COL1A1-PDGFB fusion by fluorescence in situ hybridization and reverse transcription-polymerase chain reaction analyses. To our knowledge, this is the first documented case of a genetically confirmed deep-seated DFSP without an associated superficial soft tissue or dermal component. The implication of this case on expanding the clinical spectrum of DFSP will have to be elucidated in future studies by applying molecular pathologic tools in deep-seated sarcomas in the proper morphologic context.