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Case 77.
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Non-tuberculous mycobacterial infection of lung (22 y-o M) |  |
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Apical lung lesions surgically resected after prolonged chemotherapy
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Key words :
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Non-tuberculous mycobacterium, Mycobacterium avium-intercellulare, caseous necrosis | ||||
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opportunistic infection
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| The caseous lesions are grossly indistinguishable from tuberculosis. | Histologically, caseous necrosis and epithelioid granulomatous reaction with Langhans-type giant cells are observed, being totally indistinguishable from tuberculosis (HE). | |
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| A few acid-fast bacilli are identified in the cytoplasm of macrophages (Ziehl-Neelsen). M. avium-intracellulare was cultured from the lesion. | Reference case 77A Autopsied lung of a 79 y-o male who died of massive hemoptysis (HE). Caseous necrosis is formed adjacent to the bronchus. Epithelioid cell reaction is incomplete in this case. M. avium-intracellulare was cultured. |
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| Reference case 77B Striated histiocytes in Mycobacterium avium-intracellulare infection in a 45 y-o AIDS guy (HE). Histiocytoma-like proliferation of histiocytes with striated eosinophilic cytoplasm is seen in the enlarged mediastinal lymph node. |
Reference case 77B Acid-fast bacilli filling the cytoplasm of the striated histiocytes (Ziehl-Neelsen). The striated appearance of striated histiocytes is due to impaction of Mycobacterium in the cytoplasm. |
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| Reference case 77B BCG antigens identified in the cytoplasm of the striated histocytes (immunostaining). BCG antigens recognized by a polyclonal antibody from DakoCytomation are seen on the surface of Mycobacteria and some fungi, but not on human cells. |
Reference case 77B Ultrastructural localization of BCG antigens on bacilliform microbes in paraffin section (pre-embedding immunoelectron microscopy). Structures of microbes are relatively resistant to paraffin embedding. Pre-embedding immunoelectron microscopy using paraffin sections is useful to show the specificity of immunostaining. |
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