Sarcoidosis en-plaque. Report of a case and review of the literature.

A 31-year-old black male with sarcoidosis en-plaque of the dura mater, which is a rare morphological variant of neurosarcoidosis (NS), presented at our clinic. Magnetic resonance imaging (MRI) of the head with gadolinium showed non-specific enhancement of both tentorial leaves extending to the floor of right middle cranial fossa and cavernous sinus. The laboratory results were normal except for slightly increased serum angiotensin converting enzyme (SACE) (68 U/ml n = 4-56 U/ml) and cerebrospinal fluid (CSF) IgG index (0.57, n = 0.46). Biopsy of the intracranial dural lesion was consistent with sarcoidosis. Oral steroid therapy (Methylprednisolone 4 mg QID) was started and the patient became asymptomatic. However, MRI of the brain with gadolinium 2 months after biopsy showed progression and extension of the enhanced dural lesion. His SACE level was unchanged. We concluded that progression of the enhanced lesion seen in MRI could be recently formed scar tissue, new lesion or both. MRI findings should always be correlated with clinical findings for evaluation of NS during follow-up.

Oligodendroglial hamartoma of the right temporal lobe: a case report and discussion of possible histogenesis.

A case of oligodendroglial hamartoma is reported in a 39-year-old man with a 20-year history of petit mal seizures. Magnetic Resonance Imaging of the brain showed a small focal area of abnormal decreased signal on T1-weighted images of the right temporal lobe. The patient became seizure free after the removal of the lesion and treatment with carbamazepine. Pathologic examination revealed several aggregates of oligodendroglial cells with small, dark, regularly stained nuclei and a clear, well-defined perinuclear halo; there was no mixture of neurons or astrocytes. Although these cells were negative, the background was strongly positive for glial fibrillary acidic protein, and myelin basic protein. The histopathologic diagnosis of the temporal lobe lesion was oligodendroglial hamartoma. This report documents an additional subtype of temporal lobe hamartoma associated with seizure disorder.

Localized arteriovenous malformation of the jejunum.

Arteriovenous malformations of the small intestine are a vanishingly rare cause of hemorrhage from the gastrointestinal tract. To our knowledge, only one previous case has been reported. We describe a 41-year-old man with massive gastrointestinal bleeding as the result of a jejunal arteriovenous malformation. We discuss the histologic differentiation from angiodysplasia.

Cerebral arteriovenous malformations. A detailed morphological and immunohistochemical study using actin.

Vascular musculature was studied in cerebral arteriovenous malformations using a monoclonal antibody against the muscle protein actin in 20 cases. The more typical vessels (arterial and venous types) and a number of abnormalities of the muscular layer were identified. The latter included (1) partially developed media; (2) two layers of the media separated by a well-formed internal elastic membrane; (3) total or partial disarray of the muscle coat; and (4) partial absence of the media. Previously described large capillaries proved to be postcapillary venules by virtue of having a distinct muscular layer. Serial sectioning indicated that the previously described "polypoid projections" of the media are mostly artifacts and the concept of "arterialization of veins in arteriovenous malformations" could not be substantiated. The actin method proved to be a useful adjunct to the conventional stains for accurate and selective detection of smooth-muscle cells.

Oligodendroglial proliferative abnormality associated with arteriovenous malformation: report of three cases with review of the literature.

A peculiar nonneoplastic oligodendroglial proliferative abnormality associated with cerebral arteriovenous malformations (AVMs) was present in three patients. Histological examination of biopsy material revealed dense oligodendroglial tissue reminiscent of oligodendroglioma in the white matter adjoining the AVMs. Careful consideration of clinical and pathological features suggested that the evidence was insufficient to qualify the lesion as truly neoplastic (oligodendroglioma); rather, a tissue collapse or a hamartomatous proliferation could be considered to be its cause. The literature contains 14 instances of various vascular malformations associated with primary brain tumors, 5 of which were diagnosed as oligodendrogliomas. It is possible, however, that some of the cases reported in the literature constitute oligodendroglial abnormality similar to that observed in our cases rather than genuine oligodendrogliomas. Attention is drawn to this interesting and prognostically important phenomenon.

Hyalinizing plasmacytic granulomatosis of the falx.

Computed tomography scan in a 43-year-old woman revealed a fusiform mass involving the falx. Pathological tissue removed at craniotomy revealed a hyalinizing plasmacytic granulomatosis composed of masses of lymphocytes, plasmacytes, and various sized islands of hyalinized fibers arranged in parallel and surrounded by multinucleated giant cells. Ultrastructurally, the hyalinized fibers consisted of electron-dense, amorphous deposits. After partial removal, irradiation, and steroid therapy, the lesion decreased considerably in size.