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 ti ssues such as skin, gastrointestinal tract, bone marrow, liver, spleen, and lymph nodes tend to increase. Significant mast cell burdens are most obvio us in patients with long-standing, indolent mastocytosis or with aggressive forms of the disease, such as seen in categories II and III. Patients in t hese situations may exhibit a clinically relevant increase in the size of t heir lymph nodes, liver, and spleen.(18) In routine management of patients with mastocytosis, the lymph nodes and sp leen 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 i nfiltrations and their consequences in organs such as liver, spleen, or lym ph nodes exhibit a bias for disease categories II and III. Similarly, the a vailable information is insufficient to distinguish tissue-specific disease features typical for the various categories of mastocytosis or to correlat e the appearance of the mast cells within Ctissues with the category of dis ease. What is clear, however, is that an examination of lymph; nodes and sp leen from patients with mastocytosis does reveal significant pathologic con ditions associated with mast cell infiltration.(18).