Lymphoid tissues and the immune system in mastocytosis

Involvement of the spleen and lymph nodes is an important manifestation of systemic mastocytosis. With the bone marrow, the lymph nodes and spleen are the organs most commonly infiltrated in mastocytosis. In all categories of mastocytosis, the one constant is that, over time, mast cell numbers in tissues such as skin, gastrointestinal tract, bone marrow, liver, spleen, and lymph nodes tend to increase. Significant mast cell burdens are most obvious in patients with long-standing, indolent mastocytosis or with aggressive forms of the disease, such as seen in categories II and III. Patients in these situations may exhibit a clinically relevant increase in the size of their lymph nodes, liver, and spleen.(18) In routine management of patients with mastocytosis, the lymph nodes and spleen are rarely biopsied and examined unless significant organ dysfunction has developed or unless there is suspicion of a malignant process for which a biopsy is appropriate. Thus, existing data on the pattern of mast cell infiltrations and their consequences in organs such as liver, spleen, or lymph nodes exhibit a bias for disease categories II and III. Similarly, the available information is insufficient to distinguish tissue-specific disease features typical for the various categories of mastocytosis or to correlate the appearance of the mast cells within Ctissues with the category of disease. What is clear, however, is that an examination of lymph; nodes and spleen from patients with mastocytosis does reveal significant pathologic conditions associated with mast cell infiltration.(18).