401 Postgrad Med J: first published as 10.1136/pgmj.23.263.401 on 1 September 1947. Downloaded from THE PATHOLOGY OF LYMPH NODE ENLARGEMENT By L. WOODHOUSE PRICE, M.A., M.D.(Cantab.) Director of the Pathological Department, The Royal Cancer Hospital, London Many different aetiological factors con- Histology of the Normal Lymph Node. The tribute to the enlargement of lymnph nodes; microscopic appearance is by no means in some cases the cause is obvious, in others uniform but a generalized or fundamentally obscure. The enlargement may be focal, characteristic histological picture can be de- regional or generalized, or the first two types duced from a study of a large number of lymph may progress to the third. The enlargement nodes excised for 'biopsy purposes and pre- may be the only clinical manifestation of served in various fixative solutions from which disease or it may be accompanied by various paraffin sections are prepared and stained by signs and symptoms, such as pain, pyrexia, several different technical methods. Protected by copyright. exanthemata, changes in the blood picture or It so happens that certain component parts pressure effects on viscera. of a lymph node are accentuated under the The histological differential diagnosis of influence 'of certain morbid processes, par- lymph node enlargement depends upon a ticularly inflammatory conditions and the proper appreciation of the normal structure of reticuloses. Hence, paradoxically, the normal a lymph node and of the various changes which structure is more clearly appreciated from a are common to several or peculiar to certain consideration of the histological appearances specific types of pathological processes. In *of lymph nodes which are slightly abnormal. some cases a consideration'of the clinical con- The lymph node is a spheroidal, ovoid or dition alone is sufficient to establish a correct reniform body surrounded by a delicate fibrous diagnosis. This applies especially to lymph capsule and composed of certain characteristic node enlargement associated with inflam- components which are clearly recognizable and matory lesions, acute specific fevers and which can be resolved into three essential http://pmj.bmj.com/ chronic infective granulomata. In other cases constituents, namely,' the lymphadenoid par- the. aid of histology and haematology is enchyma, the lymphadenoid follicles and the essential. The latter group comprises the lymphatic sinusoids. The majority of lymph primary lymphadenopathies and metastatic nodes are supported by a surrounding matrix tumour deposits. of adipose tissue, but certain homologous lymphoid structures are distributed in the sub- An investigation as to the cause of lymph' on September 30, 2021 by guest. node enlargement demands an account of the epithelial region of the buccal, nasal and clinical appearance of the patient, the deter- pharyngeal mucosae and the submucous tissues mination of the size, consistency and distribu- of the alimentary canal. tion of the enlarged nodes and a detailed re- The Capsule. Fully developed lymph nodes port on the histology of a node excised for are completely surrounded by a delicate biopsy purposes, to which it is often advisable fibrous capsule which is perforated by afferent to add the macroscopic appearance of the and efferent blood vessels and by afferent and hemisected node.' In certain diseases the efferent lymphatic channels. In nodes which concomitant pathological changes in other are only partially developed the capsule is organs and tissues have to be considered also. incomplete. Such nodes on hemisection in the 402 POST GRADUATE MEDICAL JOURNAL September 1947 Postgrad Med J: first published as 10.1136/pgmj.23.263.401 on 1 September 1947. Downloaded from longitudinal axis present a C-shaped or horse- soids. Trfese are div,isible anatomically into shoe outline, the convexity being covered by a the subcapsular group which forms a lymphatic capsule while the concavity is filled with lake between the capsule and the lymphadenoid adipose tissue into which lymphocytes appear parenchyma, and the medullary group in the to be diffusely permeating. This peculiar centre of the node. Between these two groups structure has an important bearing on the there is free intercommunication of lymphatic spread of metastatic tumours. channels. The subcapsular sinus is joined by The Lymphadenoid Parenchyma. This con- several afferent lymphatic channels which sists essentially of a matrix of lymphocytes and perforate the capsule around the periphery of lymphoblasts. Under conditions of reticulo the ovoid and reniform nodes and around the endothelial hyperplasia isolated elements or convexity of the C-shaped and horseshoe small groups of reticulo endothelial cells are nodes. At the hilum of the node an efferent found lying free in the matrix. This com- lymphatic channel emerges, and at this point ponent of the fundamental c6mposition of the the nutrient vessels find access and egress. normal lymph node becomes encroached upon Valves are discernible in the extra capsular by reticuloses of either the follicles or the zone in both afferent and efferent lymphatic sinusoids. It is particularly affected in certain channels. lipodystrophies and shares in the general dis- The lymphadenoid sinusoids are lined by organization of normal lymphadenoid architec- reticulo endothelial cells which also traverse ture in Hodgkin's disease. On the other hand, their lumina, converting them into a sponge- the lymphadenoid parenchyma predominates like meshwork whose interstices contain circu- over both follicles and sinusoids in lymphatic lating lymph. Protected by copyright. leukaemia and in the lymphosarcomata. Under normal conditions this sinusoidal The Lymphadenoid Follicles. Around the meshwork is difficult to detect in routine periphery of the node there are circumscribed histological preparations but it is readily dis- spheroidal or ovoid bodies known as the cernible under conditions of reticulo endo- lymphadenoid follicles, the lymph follicles or thelial hyperplasia and catarrhal conditions of the germ centres of Flemming. These con- the sinusoids. In certain lipodystrophies the sist of a core of reticulo endothelial cells sinusoids become distended with lipoid con- surrounded by several concentrically laminated taining cells, and in lymphogenous metastasis layers of lymphocytes. Normally, the central of malignant tumours they contain plugs of zone of reticulo endothelial cells is incon- specific neoplastic cells. spicuous but a hyperplastic reaction is readily Pathological Changes in Lymph Nodes. invoked by any slight inflammatory process. Various types of cellular response are en- Nodes excised for biopsy purposes are, ipso countered in lymph nodes as component http://pmj.bmj.com/ facto, to some extent pathological. However manifestations of various diseases. Any or all inconspicuous they may be, the presence of of the three essential elements of the lymph the central zone of reticulo endothelial cells uo-e may be affected to a greater or less and the lamination of the surrounding lympho- extent. Thus the follicles and sinusoids may cytes are essential to the composition of the become unduly prominent due to reticulo true follicle. endothelial hyperplasia or they may become on September 30, 2021 by guest. It is readily understandable that the plane of obliterated or modified by cellular prolifera- the section may pass through the boundary tion of the lymphadenoid parenchyma. Patho- zone of a complete follicle so that only a logical changes may also be caused by the circumscribed aggregate of lymphocytes ap- advent of extraneous cells not normally found pears in the microscopic field; such collec- in the lymph node, as exemplified by the tions are referred to as ' pseudofollicles.' malignant epithelial cell in metastatic car- The Lymphadenoid Sinusoids. The lym- cinoma. phadenoid parenchyma is permeated by a The pathology of lymph node enlargement meshwork of lymphatic channels which inter- may conveniently be described under the communicate and which constitute the sinu- following main headings:' Postgrad Med J: first published as 10.1136/pgmj.23.263.401 on 1 September 1947. Downloaded from September 1947 WOODHOUSE PRICE: Pathology of Lymph Node Enlargement 403 i. Acute Lymphadenitis. In cases which do not proceed to suppura- 2. Chronic Lymphadenitis. tion, complete or partial resolution follows. 3. The Reticuloses and Lipodystrophies. Resolution is preceded by deposition of fibrin 4. Primary Lymphadenopathies. in the sinuses, followed by fibrosis and 5. Secondary Lymphadenopathies. subsequent phagocytosis, and the affected 6. The differential diagnosis of specific cases node may eventually be restored to its normal of lymph node enlargement. morphology. In some cases, however, fibrosis persists owing to the continued presence of infecting organisms of impaired virulence, and Acute Lymphadenitis the acute form of lymphadenitis leads to its Aetiological factors are exemplified by acute chronic counterpart. infection of the skin with pyogenic cocci, of the 'tonsils with streptococci, of the naso- pharynx with the Klebs-Loeffler bacillus and Chronic Lymphadenitis of the urethra with Neisserian organisms. Certain non-specific forms of chronic Macroscopically the regional lymph nodes lymphadenitis are more conveniently con- present the classical signs of inflammation, sidered in relation to reactionary reticuloses. accompanied in fulminating cases by acute Those forms which are due directly to specific lymphangitis. On