Epithelioid cellular chordoma of the sacrum: a potential diagnostic problem

IFI6 Inhibits Apoptosis via Mitochondrial-Dependent Pathway in Dengue Virus 2 Infected Vascular Endothelial Cells

Dengue hemorrhagic fever (DHF)/Dengue shock syndrome (DSS) is a fatal infectious disease that demands an effective treatment. Interferon (IFN)-stimulated genes (ISGs) induced by dengue virus (DENV) exert antiviral effects. Among ISGs, IFN-α inducible gene 6 (IFI6) was increased in DENV infected human umbilical vascular endothelial cells (HUVECs) by microarray analysis in our previous study. However, its function is incompletely understood. In this study, we confirmed that IFI6 was markedly induced in DENV infection of both primary HUVECs and EA.hy926 cell lines. Recombinant EA.hy926 cell lines in which IFI6 was either over-expressed (IFI6+/+) or knocked-down (IFI6-/-) were generated. The activation of caspase-3 and intrinsic apoptosis-related protein caspase-9 were down-regulated in IFI6+/+ but up-regulated in IFI6-/- cells at 24–48 hrs post-infection. After incubation with DENV for 48 hrs, the mitochondrial membrane potential (Δψ(m)) was more stable in IFI6+/+ cells but reduced in IFI6-/- cells, as assayed by fluorescence staining with JC-1. We observed that Bcl-2 expression was increased in IFI6+/+ and decreased in IFI6-/- cells. By contrast, Bax expression was decreased in IFI6+/+ and increased in IFI6-/- cells. It is presumed that the anti-apoptotic function of IFI6 is expressed by regulating the rheostatic balance between bcl-2/bax expression and inhibition of Δψ(m) depolarization during DENV infection of vascular endothelial cells(VECs). In addition, the pro-apoptotic protein X-linked Inhibitor of Apoptosis (XIAP)-Associated Factor 1(XAF1) expression had been reported to be up-regulated and led to the induction of apoptosis in DENV2-infected VECs,but the relationship between XAF1 and IFI6 dengue virus-induced apoptosis in VECs warrants further study.

Possible parachordoma in a dog

CASE HISTORY

A 15-mm diameter mass developed in the S/C tissue overlying the right lateral gluteal muscle of a 6(1/2)-year-old female Flat-coated Retriever.

PATHOLOGICAL FINDINGS

Cytological preparations following aspiration of the mass were highly cellular and consisted of a population of large polygonal cells containing single to multiple nuclei, large prominent nucleoli, and intracytoplasmic vacuoles. Histologically, the neoplasm consisted of similar large cells surrounded by thick fibrous connective tissue trabeculae. The large polygonal cells reacted positively with antibodies against vimentin, low- and high-molecular-weight variants of cytokeratin (AE1/AE3), but not with antibodies to desmin or glial fibrillary acidic protein (GFAP).

DIAGNOSIS

The clinical, gross, histological and immunohistochemical findings are similar to those reported for parachordomas in humans. Neither recurrence nor metastases were noted 18 months after surgical excision of the mass.

CLINICAL RELEVANCE

This is the first reported case of a possible parachordoma in a dog, a benign tumour with cytological features of malignancy.

Dedifferentiated chordoma of the thoracic spine with rhabdomyosarcomatous differentiation. Report of a case and review of the literature

A case of spinal thoracic chordoma involving the T9 vertebra in a 70-year-old male patient, destroying the vertebral body and invading the vertebral canal with compression of the spinal cord, is presented. The patient was referred to our neurosurgical unit with a history of an irradiated metastatic adenocarcinoma to the thoracic vertebra, a diagnosis that was rendered 3 years earlier at another hospital on presentation. This misdiagnosis was likely due to the absolute rarity of thoracic vertebral chordomas (2%-3% of all chordomas), the higher frequency of metastatic deposits to the vertebrae from visceral cancers in the elderly, the limited amount of biopsy material available for histologic examination, and the epithelial phenotype of the tumor (keratin/EMA positive). The patient underwent second palliative surgery with subtotal piecemeal removal of the tumor bringing relief of the neurologic symptoms. The bulk of the tumor was represented by a high-grade pleomorphic sarcoma with adjacent areas of atypical chordoma. Small foci of conventional chordoma were also found. The previous histologic slides were also reviewed, which were consistent with the areas of atypical chordoma. Small targeted tissue fragments from areas of (atypical) chordoma and from sarcomatous areas were recovered for electron microscopy. The fine features of chordoma and focal rhabdomyoblastic differentiation were found with the latter retrospectively supported by immunohistochemical detection of striated muscle markers. A final diagnosis of dedifferentiated chordoma with rhabdomyoblastic differentiation was finally established. Rhabdomyoblastic metaplasia is a novelty in dedifferentiated chordoma. The patient died after 5 months. Autopsy was not requested.

Epithelioid and Epithelial Neoplasms of Bone

Context.—Epithelioid and epithelial neoplasms seen in bone are rare and include epithelioid variants of vascular lesions, osteoblastoma, osteosarcoma, chordoma, and chondroblastoma as well as adamantinoma and metastatic carcinoma.

Objective.—To provide an overview of tumors with epithelioid histology and address the clinical context and diagnostic issues.

Data Sources.—Pertinent literature is reviewed with emphasis on recent and controversial issues.

Conclusions.—The differential diagnosis in epithelioid/ epithelial lesions of bone is limited. The primary consideration in many cases is distinguishing primary from metastatic lesions.