Lymphoid follicular hyperplasia

In a biopsy of an AIDS patient s enlarged thymus (P4), the adipose involuted thymus, with persistence of many Hassall s corpuscles, was judged to be a large lymphoid follicular hyperplasia. This follicular hyperplasia was similar to that described for lymph nodes, spleen, and other lymphoid tissues at earlier stages of human immunodeficiency virus infection, before the development of acquired immune deficiency syndrome. Human immunodeficiency virus RNA and p 24 were detected in the hyperplastic germinal centers (lymphocytes and follicular dendritic infected cells) and also in many cells that may have been either lymphocytes or epithelial cells in the interfollicular areas. 

Gastric erosions are aphthous ulcers that do not penetrate the muscularis mucosa. They are most often related to H. pylori infection (Levine and Rubesin 1995). Other causative agents include alcohol, salicylates, and nonsteroidal anti-inflammatory drugs (NSAIDs). They are also seen in critically ill patients due to multiple trauma, sepsis, shock, etc. At double-contrast barium studies, gastric erosions appear as shallow small, 1-2-mm-diameter collections of barium surrounded by a radiolucent rim of oedema an appearance mirrored at endoscopy with a haemorrhagic centre and oedematous rim (Fig. 5.2a,b) (Levine and Rubesin 1995 Sohn et al. 1995 Dheer et al. 2002). H. pylori infection is also related to the presence of lymphoid follicular hyperplasia, which is commonly present in patients with peptic ulcer disease (Fig. 5.3a,b) (Torigian et al. 2001). 

Limpens J, de Jong D, van Krieken JH, Price CG, Young BD, van Ommen GJ, Kluin PM. Bcl-2/JH rearrangements in benign lymphoid tissues with follicular hyperplasia. Oncogene 1991 6 2271-6. 

The principal differential diagnosis is MALT lymphoma, lymphoid interstitial pneumonitis, and follicular hyperplasia of BALT. Pertinent features of the differential diagnosis are shown in Table 2. 

This name, also termed follicular hyperplasia of BALT, refers to the presence of lymphoid aggregates, usually with reactive follicles, next to and confined to the walls of the airways and septal areas (81). This pattern of inflammation can be seen in a variety of diseases, including HIV infection/AIDS, where it is called... 

The lymphoplasmacytic interstitial infiltrates seen in UIP are generally sparse in comparison to other entities such as nonspecific interstitial pneumonia (NSIP) or hypersensitivity pneumonitis (HP). Extensive cellular infiltrates or follicular lymphoid hyperplasia should lead to consideration of other entities that may cause a UIP pattern of fibrosis such as CVD or HP. Pleural inflammation is not a feature of idiopathic UIP, and its presence indicates a second process or secondary form of UIP with pleuritis, most likely a CVD such as rheumatoid arthritis (RA) or systemic lupus erythematosus (SUE) (14). 

CVD, especially lupus, and drug toxicity can cause a picture of DAD identical to AIP. Histologic clues to the presence of CVD include pleural inflammation, follicular lymphoid hyperplasia, and the presence of capillaritis, which is engorgement of alveolar capillaries with numerous neutrophils (14). 

BALT in normal man is sparse, but a striking reactive lymphoid proliferation can occur in disease. These hyperplastic changes can differ in extent and location within the lung. This is the case in reactive lesions such as follicular bronchiolitis, lymphocytic interstitial pneumonia (LIP), and nodular lymphoid hyperplasia (NLH). 

As noted above, LIP is part of a spectrum of pulmonary lymphoid proliferations, ranging from follicular bronchitis-bronchiolitis to low-grade malignant lymphoma, patterns which may be difficult to distinguish from each other (5). When reactive lymphoid nodules are centered in a lymphatic distribution about airways, vessels, and interlobular septa, the disease is termed follicular bronchitis/ bronchiolitis [or pulmonary lymphoid hyperplasia (PLH)] in the pediatric AIDS literature) (60). As the disease becomes more florid and the reactive lymphoid infiltrate extends into the lung interstitium, then the process is termed LIP (3). 

Table 2 Differential Diagnosis of Nodular Lymphoid Hyperplasia (NLH), Lymphocytic Interstitial Pneumonia (LIP), Follicular Bronchiolitis (FB), and Extranodal Marginal Zone Lymphoma (Maltoma)... 

Fig. 4.31a,b. Duodenal nodules. The different causes all show very distinct patterns that are easy to confuse at endoscopy, a Follicular lymphoid hyperplasia, b gastric metaplasia ( spilling out of the pylorus )... 

Fig. 5.3a,b. Follicular lymphoid hyperplasia a double-contrast barium meal study shows follicular lymphoid hyperplasia involving the antrum, b A second patient shows antral follicular lymphoid hyperplasia with an associated pyloric ulcer... 

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