Rare pneumoconiosis induced by long-term amorphous silica exposure: the histological characteristics and expression of cyclooxygenase-2 as an antifibrogenic mediator in macrophages.

Pneumoconiosis induced by non-crystalline silica is considered rare, although silicosis resulting from contact with crystalline silica is a well-known hazard associated with progressive pulmonary fibrosis. Here we describe a patient with pneumoconiosis induced by diatomaceous earth composed of amorphous silica detected by two-dimensional imaging of chemical elements. The histology revealed that the disease was characterized by a granulomatous reaction in the lung. A large number of macrophages laden with yellow and black pigments accumulated in alveolar spaces and were incorporated into the interstitial sites. Bronchiolar walls were destroyed by palisade macrophages, suggesting airflow obstruction. Packed macrophages adhering to and covering the denuded interstitium indicated that macrophages might be incorporated into pulmonary interstitium in this fashion. Immunohistochemistry showed that cyclooxygenase-2, an antifibrogenic mediator, was intensely expressed in the macrophages compared with macrophages in control lungs. No birefringent material was found in the tissues. When two-dimensional analysis of chemical elements was performed using an electron probe microanalyzer with a wavelength-dispersive spectrometer, the resultant fine mapping of silicon and oxygen on the tissue indicated that the pigments phagocytosed by macrophages corresponded to amorphous silica. In conclusion, two-dimensional analysis of elements is very useful for pathologists in correlating the presence of chemical elements with histological changes.

Necrotizing lymphadenitis (NEL) is a systemic disease characterized by blastic transformation of CD8+ cells and apoptosis of CD4+ cells.

This clinicopathological, immunohistochemical, electron microscopic, and serological study of 382 cases (148 male, 234 female) of necrotizing lymphadenitis (NEL) in Japan confirms NEL as a self-limited disease with characteristic clinical features: high fever (38-40 °C), painful cervical lymphadenopathy (88.3 %), and leukopenia (under 4,000/mm(3)) without seasonal occurrence. Patient age varied from 5 to 80 years, but 62.8 % was younger than 30 years. There were five recurrent cases and four familial cases. In several cases, elevated serum aminotransaminase and antinuclear antibodies were found. Early in the disease, peripheral blood CD8+ cells were more abundant than CD4+ cells, but CD8+ cells decreased gradually with clinical progression, leading to an increasing ratio of CD4+/CD8+ cells during clinical course. Morphological features of involved lymph nodes are numerous CD8+ large immunoblasts, smaller CD4+ lymphocytes, plasmacytoid dendritic cells, histiocytes, and macrophages, the latter with phagocytized CD4+ apoptotic lymphocytes. Granulocytes are generally absent. These characteristics suggest that NEL is a reactive disease characterized by diploid disrupted CD4+ cells and CD8+ cells transforming to blastic cells. The etiology of the disease remains unknown, although viral infection is suggested, and its pathogenesis might include autoimmunity. Clinical characteristics and cytological and histological findings on lymph node biopsies can improve NEL diagnosis.

Temporal differences of onset between primary skin lesions and regional lymph node lesions for tularemia in Japan: a clinicopathologic and immunohistochemical study of 19 skin cases and 54 lymph node cases.

For tularemia, a zoonosis caused by the gram-negative coccobacillus Francisella tularensis, research of the relation between skin lesions and lymph node lesions has not been reported in the literature. This report describes skin lesions and lymph node lesions and their mutual relation over time for tularemia in Japan. Around the second day after infection (DAI), a subcutaneous abscess was observed (abscess form). Hand and finger skin ulcers formed during the second to the fourth week. Subcutaneous and dermal granulomas were observed with adjacent monocytoid B lymphocytes (MBLs) (abscess-granulomatous form). From the sixth week, large granulomas with central homogeneous lesions emerged diffusely (granulomatous form). On 2-14 DAI, F. tularensis antigen in skin lesions was detected in abscesses. During 7-12 DAI, abscesses with adjacent MBLs appeared without epithelioid granuloma (abscess form) in regional lymph nodes. During the second to fifth week, granulomas appeared with necrosis (abscess-granulomatous form). After the sixth week, large granulomas with a central homogeneous lesion (granulomatous form) appeared. F. tularensis antigen in lymph node lesions was observed in the abscess on 7-92 DAI. Apparently, F. tularensis penetrates the finger skin immediately after contact with infected hares. Subsequently, the primary lesion gradually transfers from skin to regional lymph nodes. The regional lymph node lesions induced by skin lesion are designated as dermatopathic lymphadenopathy. This study revealed temporal differences of onset among the skin and lymph node lesions.