This memorandum provides guidelines on the definition, nomenclature, and classification of cirrhosis, chronic hepatitis, and hepatic fibrosis. These are considered according to morphological characteristics and aetiology. It is hoped that this system will serve as a standard for diagnostic, research, and epidemiological purposes. The relationship of cirrhosis to liver cell carcinoma is briefly discussed and the possible morphological markers of an increased risk of malignancy are defined.

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SUMMARY Cervical, axillary, cubital, inguinal, popliteal, and mesenteric lymph nodes from subjects of various ages who had died a sudden death were examined histologically. Care was taken to establish by morphometry the proportional distribution in lymph node cross-sections of cortical, paracortical, and medullary areas. In addition, numbers and surface areas of cross-sectioned germinal centres were registered. Important differences related to age and anatomical site of lymph nodes were established by this survey. Germinal centre formation, particularly evident in infants and children, less so in young adults, and often absent in ageing individuals, was most impressive in lymph nodes normally exposed to antigenic stimulation (mesenteric and cervical lymph nodes). Paracortical and medullary areas exhibited a slight but gradual reduction with advancing age. Replacement of lymphatic parenchyma by fat tissue (lipomatous atrophy) was a characteristic of more peripheral lymph nodes usually subjected to little antigenic stimulation, that is, cubital, axillary, and popliteal nodes. It should be emphasised that both age-related and regional differences have to be taken into account in a meaningful functional interpretation of lymph node morphology.The lymph node system constitutes the major part of the peripheral lymphoid tissues in the mammalian organism. Because they drain anatomically distinct tissue areas, these structures often represent the primary sites of interaction between antigenic material and immunologically competent cells. Hence, structural changes in lymph node morphology directly reflect local immune reactivity.The possibility that information on immunological function may be gained from registering changes in lymph node architecture and cellularity1 has both theoretical and practical implications.For instance, correlation of lymphoid tissue morphology with other parameters of immune responsiveness in animal experiments greatly enhanced our knowledge of age-related differential changes in T and B cell-mediated immunity.2 Associations between lymph node morphology and prognosis have been demonstrated for cancers of lung, cervix, colon, and breast. [3][4][5][6] It is of practical importance that in the diagnostic

The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy. the Department of Defense. or the Uniformed Services Univer. sity of the Health Sciences. s RSNA, 1992 366 U RadioGraphics U Buck et a! Volume 12 Number 2 sented, based on a review of the 40 cases in the radiology archives of the Armed Forces Institute of Pathology and of the literature.

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