For example, laboratory studies show that: 1) follicular dendritic cells, fibroblastic reticular cells, and T helper cells provide growth and survival signals to neoplastic follicular B-cells; 2) neoplastic follicular B-cells recruit regulatory T cells that act to suppress immune responses to them; 3) the cytotoxic T-cells which normally kill neoplastic cells become dysfunctional in the presence of neoplastic follicular cells that are embedded in this multicellular environment; and 4) bone marrow stromal cells directly support the growth of neoplastic follicular cells. Reduced levels of immune-infiltration has been shown to be strongly associated with early progression of disease. Presentation and course
In situ follicular lymphoma
FL is commonly preceded by but uncommonly progresses to ISFL, an asymptomatic disorder that usually is discovered in tissues which are biopsied for other reasons. FL lymphoma may be diagnosed in the uncommon  cases in which individuals with ISFL are found to have FL on follow-up examinations. Similarly, individuals with >1 in 10,000 circulating lymphocytes containing the t(14:18)q32:q21) translocation are at increased but still small risk of developing FL and being diagnosed as having FL on follow up examinations. Follicular lymphoma
FL commonly presents as an otherwise asymptomatic enlargement of lymph nodes in the neck, armpit, groin, femoral canal, or other sites in individuals (median age 65) without a known history of ISFL or abnormal numbers of circulating t(14:18)q32:q21-conatianing lymphocytes. These enlargements may have been present for months to years and during this time waxed and waned in size.
Lymphangioma circumscriptum, a microcystic lymphatic malformation, resembles clusters of small blisters ranging in color from pink to dark red. They are benign and do not require medical treatment, although some patients may choose to have them surgically removed for cosmetic reasons. Cavernous lymphangiomas are generally present at birth, but may appear later in the childs life. These bulging masses occur deep under the skin, typically on the neck, tongue and lips, and vary widely in size, ranging from as small as a centimeter in diameter to several centimeters wide. In some cases, they may affect an entire extremity such as a hand or foot. Although they are usually painless, the patient may feel mild pain when pressure is exerted on the area. They come in the colors white, pink, red, blue, purple, and black; and the pain lessens the lighter the color of the bump. Cystic hygroma shares many commonalities with cavernous lymphangiomas, and some doctors consider them to be too similar to merit separate categories. However, cystic lymphangiomas usually have a softer consistency than cavernous lymphangiomas, and this term is typically the one that is applied to lymphangiomas that develop in fetuses. They usually appear on the neck (75%), arm pit or groin areas. They often look like swollen bulges underneath the skin. Causes
The direct cause of lymphangioma is a blockage of the lymphatic system as a fetus develops, although symptoms may not become visible until after the baby is born. The cause remains unknown.