Lipomatous meningioma: a clinicopathologic study of 18 cases with special reference to the issue of metaplasia.

We report 18 cases of lipomatous meningioma occurring in patients aged 14 to 79, most being females (72%). Sixteen were supratentorial and 2 involved the spinal meninges. Follow-up ranged from 1 to 120 months. Fifteen patients were cured with surgery alone and 3 (17%) experienced a recurrence at 7, 8 and 24 months. Of these, one died with disease 4 years after resection of the primary lesion. Histologically, 12 tumors were meningothelial, 3 transitional, 2 showed myxoid stromal changes and 1 was microcystic. The 2 spinal tumors were atypical. The proportion of fatty cells ranged from 10 to 90%. These resembled mature adipocytes or less commonly lipoblasts. Xanthomatous meningothelial cells were also noted in 6 tumors (30%). Both conventional meningothelial as well as lipid-laden cells exhibited epithelial membrane antigen immunoreactivity. In addition, occasional cells resembling mature adipocytes showed reactivity for S-100 protein. Ultrastructurally, lipidization of neoplastic cells varied from intracytoplasmic lipid droplets to a single massive globule. Moreover, lipid-laden meningothelial cells featured interdigitating cell membranes and well-formed desmosomes. Lipid droplets were not membrane-bound. In that metaplasia denotes differentiation of one mature cell type to another, lipid accumulation in meningiomas cannot be considered true metaplasia since their lipid-laden cells retain the immunophenotype and ultrastructural features of meningothelium. We suggest that this distinctive subset of meningiomas be termed "lipidized meningiomas" rather than being included in the metaplastic category.

Munchausen syndrome presenting as pulmonary talcosis.

We describe a patient with self-induced inhalational pulmonary talcosis originally diagnosed as asthma. A 35-year-old female respiratory technologist developed severe asthma that was refractory to steroids and methotrexate. An open lung biopsy specimen showed scattered aggregates of refractile golden crystals within membranous and respiratory bronchioles. The particles ranged in size from 30 to 100 microm and were birefringent when viewed with polarized light. Following review of the lung biopsy specimen, the patient admitted to regularly inhaling large amounts of hospital baby powder. Analysis of the lung biopsy specimen and a sample of the hospital baby powder by x-ray energy dispersion showed identical spectroscopic peaks, including elemental peaks for magnesium silicate. Many patients with self-induced illness lack the picturesque symptomatology classically attributed to Munchausen syndrome. Awareness of these more subtle and varied patterns of presentation may aid in earlier recognition.

Nigral neurons are likely to die of a mechanism other than classical apoptosis in Parkinson's disease.

The finding of apoptosis in Parkinson's disease (PD) represents a contentious issue. In fact, there is increasing evidence that an alternative mechanism of cell death is at work in the parkinsonian substantia nigra, which we tentatively term aposklesis. Unlike apoptosis, aposklesis ("withering") lacks the morphological signs of apoptosis and takes a slow course which is in agreement with the predicted rate of dopaminergic cell death in PD. Cells undergoing aposklesis may stain positive in the TUNEL reaction and show a reticular nuclear labeling but lack any significant chromatin condensation and the formation of apoptotic bodies. Not only neurons but also glial cells appear to undergo this form of cell death, which represents a relatively common finding in degenerative diseases of the CNS.

"Rhabdoid" meningioma: an aggressive variant.

It is has been suggested that rhabdoid morphology is associated with a poor prognosis, regardless of tumor histogenesis. We report a series of 15 meningiomas with rhabdoid features. Nine patients had undergone multiple resections. In six, the rhabdoid component was histologically apparent only in recurrences. Rhabdoid morphology was defined as sheets of loosely cohesive cells with eccentric nuclei and hyaline, paranuclear inclusions. Ultrastructurally, the latter consisted of whorls of intermediate filaments often entrapping lysosomes or other organelles. Meningothelial features included whorl formation and nuclear pseudoinclusions, immunohistochemical coexpression of vimentin and epithelial membrane antigen, and the ultrastructural finding of interdigitating cell membranes and intercellular junctions. At the histologic level, a conventional meningioma component was noted in most tumors; only four lesions were entirely rhabdoid. Histologic malignancy (brain invasion or anaplasia) was observed in nine cases, another two tumors being considered malignant on the basis of extracranial metastasis. In the majority, increased cell proliferation was evidenced by a high mitotic rate or MIB-1 LI. At last follow-up, 13 patients (87%) had experienced at least one recurrence and 8 (53%) were dead of disease. Median time to death was 5.8 years after initial surgery and 3.1 years after the first appearance of rhabdoid morphology. Our findings corroborate those from a smaller series recently reported by Kepes et al. on the same entity (Kepes JJ, Moral LA, Wilkinson SB, Abdullah A, Llena JF. Rhabdoid transformation of tumor cells in meningiomas: A histologic indication of increased proliferative activity. Report of four cases. Am J Surg Pathol 1998;22:231-8). They further suggest that rhabdoid meningiomas are highly aggressive tumors and that the rhabdoid phenotype represents a marker of malignant transformation in meningiomas.

Clinical utility of the alizarin red S stain on permanent preparations to detect calcium-containing compounds in synovial fluid.

The alizarin red S stain for permanent cytologic preparations is a valuable test that is complementary to compensated polarized light microscopic examination to detect calcium crystals. Alizarin red S has the greatest sensitivity for detection of calcium pyrophosphate crystals because crystals are stained regardless of how weakly or strongly birefringent they may be. Alizarin red S stain does not distinguish between amorphous types of calcium compounds; therefore, the different types of calcium compounds can be distinguished only when typical crystal morphologic features are present. Diagnostic importance can be attached to intracellular material that is stainable. In contrast, the diagnostic value of stainable, amorphous, extracellular material is unreliable because it is difficult to distinguish this extracellular material from contaminants frequently found in clinical specimens. Alizarin red S does not stain monosodium urate or corticosteroid crystals. Air-dried cytospin smears are helpful because they may frequently demonstrate more crystals than the wet-mount preparation. Furthermore, special stains can be performed subsequently on air-dried cytospin smears if necessary.

Particle shedding and migration from silicone genitourinary prosthetic devices.

Of 26 patients undergoing revision of genitourinary prostheses the surrounding reactive fibrous capsule was biopsied in 25 and the draining lymph nodes also were biopsied in 4. The prostheses included 16 inflatable and 14 flexible penile devices, and 10 artificial urinary sphincters. Tissue was examined by light and transmission electron microscopy. X-ray microanalysis was done on intracellular and extracellular foreign material from each specimen. Silicone was found in 18 of the 25 periprosthetic specimens and in all 4 lymph nodes. Foreign body granulomas were identified in 14 of these 29 specimens. Examination of new and explanted versions of each prosthesis by scanning electron microscopy revealed free particles of silicone or silicates on the surface of most devices. Pitting and microfissuring were seen on a few of the new devices and on nearly all of the used ones. Thus, genitourinary prostheses shed silicone particles that can be found in the fibrous capsule and draining lymph nodes.