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Bullet wounds causing lead synovitis in the wrist and knee are reported in two patients, one of whom also developed clinical plumbism. Very high lead levels in the synovial fluid are believed to be responsible for toxicity changes that occurred in the synovium and bone. Ultrastructurally, these alterations included the formation of nuclear lead inclusions, dilation, and degranulation of the rough endoplasmic reticulum and deposition of crystalline precipitates in the matrix of the mitochondria in macrophages, osteoclasts, and synoviocytes, as well as the development of cytoplasmic lead inclusions in osteoclasts. Energy-dispersive x-ray elemental analysis (EDXEA) indicated that the nuclear inclusions contained only lead, whereas precipitates within the mitochondria and elsewhere in the cytoplasm were composed of complexes containing lead, calcium, and phosphorus. Similarly constituted extracellular complexes were incorporated into newly formed trabecular bone laid down as a physiologic response to the bullet lodged within the wrist bones. This bone subsequently exhibited defects in bone resorption, which were characterized by depressed osteoclastic function and a unique lesion termed incomplete osteocytic osteolysis. The genesis of this latter lesion is uncertain. The sequestration of the partially degraded bone fragments containing lead complexes into the marrow and eventually into the joint spaces and synovium permitted the recycling of bone lead, and this may have played an important role in inducing clinical plumbism in one of the patients in this study.

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Lafora's disease is a neurometabolic disease characterized by progressive myoclonus epilepsy. It is thought to be transmitted by autosomal recessive inheritance. The diagnosis of Lafora's disease is based on both clinical symptomatology and histologic detection of intracytoplasmic periodic acid-Schiff-positive inclusions, termed Lafora bodies. Despite the absence of cutaneous clinical findings, typical inclusions are present in eccrine duct cells and peripheral nerve of skin biopsies. By electron microscopy, the inclusions are electron-lucent and contain glycogenlike granules and filamentous material. Skin biopsy is a convenient and the least invasive method of establishing the diagnosis of Lafora's disease.

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We studied a patient with relapsing idiopathic chronic eosinophilic pneumonia. Each one of four attacks observed during a 4-year period was characterized by dyspnea, wheezing, peripheral blood eosinophilia, elevated serum IgE levels, and pulmonary infiltrates. Glucocorticoid therapy caused prompt resolution of symptoms and disappearance of blood eosinophilia and pulmonary shadowing. Electron microscopy and tissue immunofluorescence studies for major basic protein documented extensive eosinophil degranulation and the presence of free granules within the pulmonary microvasculature. In addition, exfoliation of the alveolar lining cell was observed in association with a clustering of free intact and disintegrating extracellular eosinophil granules against a denuded basement membrane. These findings suggest a cytotoxic potential of the eosinophil at the level of the pulmonary parenchyma in a case of idiopathic chronic eosinophilic pneumonia.

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A case of focal priapism of the clitoris caused by a microscopic granular cell tumor (GCT) is described. This neoplasm is considered locally aggressive because it invades the lumens of peripheral cavernous sinuses of the crus of the clitoris. Caverns adjacent to those invaded by tumor exhibit stasis, telangiectasia, and necrosis of the smooth muscle of the trabecular wall. These alterations lead to telescoping collapse and compression of the cavernous spaces and culminate in fibrosis. Ultrastructurally, replicated basal lamina is found surrounding clusters of granular cells. We suspect that the multilayered lamina, in addition to being produced by tumor cells, is derived from the trabecular endothelium surrounding the caverns invaded by the GCT. The replication of the basal lamina may be provoked by cycles of injury and repair to these vessels caused by repeated episodes of prolonged vascular stasis. A peculiar large vein with perforating branches was observed in the center of the cavernous spaces of the crus. This vein is not found in normal crura and, therefore, represents a morphologic adaptation created to drain the cavernous spaces.

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Electron microscopic examination in a case of papular xanthoma revealed the presence of myelinlike laminated bodies in the cytoplasm of the foam cells. To our knowledge, similar bodies have been described in large numbers in only two cases of congenital self-healing histiocytosis and one case of generalized eruptive histiocytoma. The presence of laminated bodies may be a morphologic characteristic of papular xanthoma. However, this possibility should be confirmed by identification of the same inclusions in other cases of this disease.

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A variety of silicotic lesions derived from thoracic silicosis via lymphohematogenous spread to the liver, spleen, bone marrow, and extrathoracic lymph nodes are described. The morphologic features of these lesions depend on the extent of macrophage aggregation, the occurrence of fibrogenesis, and the development of necrosis and degradative changes in macrophages and adjacent extracellular matrix, presumably caused by lysosomal enzymes released from macrophages. Ultrastructurally, the degenerative alterations of matrix material include longitudinal splitting and breakage of collagen fibrils into segments one and three quarters the length of the original fibrils and deposition of flocculent electron-dense material either focally or diffusely around collagen fibrils. The corresponding changes viewed light microscopically are those of fibrinoid necrosis. The sclerohyaline nodule, the characteristic lesion of silicosis, includes all of these features as it evolves through nodular histiocytic and subsequent fibrohistiocytic phases. Its ultimate morphology appears to be determined by the reassembly of the degraded matrix into non-native, fibrous long-spacing collagen via a spiny collagen intermediary. The sclerohyaline nodule occurs infrequently in the spleen and liver, although less typical lesions caused by silica alone or admixed with other dusts seem to occur more commonly in these organs. These lesions appeared as loose or nodular histiocytic or fibrohistiocytic aggregates. Nonspecific fibrous nodules or more extensive fibrosis, as seen in portal triads, may represent advanced stages of such lesions. Acute or healed focal segmental glomerulonephritis occurred in 40 per cent of the cases, suggesting that it may be an important remote effect of silicosis. Continuous destruction of lymphocytes adjacent to silicotic nodules may be an antigenic source of the high concentration of autoimmune reactants described in silicosis.

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Orf is an occupational skin disease acquired through contact with infected animals. In humans, orf is usually a self-limited disease that resolves spontaneously within four to 24 weeks. We report a case with multiple lesions of orf, acquired by contact with a wild sheep. The patient was temporarily immunosuppressed by a concomitant viral hepatitis. We reviewed the histologic and electron microscopic findings. Also, we attempted to stain the Parapoxvirus in the skin of the patient, using the immunoperoxidase technique. The antiserum was obtained from sheep immunized against orf. We used lesional skin from sheep infected with orf as a positive control. The negative results of this technique in the patient's skin indicated that Parapoxvirus infecting wild sheep is antigenically different from that causing the disease in domestic animals.

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