Lymphoid hyperplasia is the rapid proliferation of normal lymphocytic cells that resemble lymph tissue which may occur with bacterial or viral infections. The growth is termed hyperplasia which may result in enlargement of various tissue including an organ, or cause a cutaneous lesion.

Lymph node anatomy

A lymph node is small, capsulated lymphoid organ that is present along the lymphatic system. It is composed of cortex and medulla. The cortex is also divided into outer cortex and inner cortex (also known as the paracortex). The outer cortex is composed of follicles of B cells so that it is called the B-cell zone. Similarly, the inner cortex has

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

s and is called the T-cell zone.

Cutaneous hyperplasia

Cutaneous Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different d ...

lymphoid lesions may be observed in follicular, granulomatous or lymphoreticular pathologic patterns. Cutaneous lymphoid hyperplasia is generally not malignant, but in rare cases an association has been observed.

Follicular hyperplasia

Follicular hyperplasia is a stimulation of the B cell compartment. It is caused by an abnormal proliferation of secondary follicles and occurs principally in the cortex without broaching the lymph node capsule. The follicles are cytologically polymorphous, are often polarized, and vary in size and shape. Follicular hyperplasia must be distinguished from

follicular lymphoma Follicular lymphoma (FL) is a cancer that involves certain types of white blood cells known as lymphocytes. The cancer originates from the uncontrolled division of specific types of B-cells known as centrocytes and centroblasts. These cells norma ...

(bcl-2 protein is expressed in neoplastic follicles, but not reactive follicles).

Paracortical hyperplasia

Paracortical hyperplasia is the preferential stimulation of the T cell compartment. It is caused by an abnormal expansion of the interfollicular zones but is confined within the lymph node capsule. The population of the compartment is cytologically polymorphous. Paracortical hyperplasia may be accompanied by vascular proliferation. Must be distinguished from monomorphous T cell lymphoma.

Sinus hyperplasia

Sinus hyperplasia is the preferential stimulation of the histiocytic (tissues macrophage) compartment. Histological features include distention or engorgement of both subcapsular and intraparenchymal sinuses by benign

histiocytes A histiocyte is a vertebrate cell that is part of the mononuclear phagocyte system (also known as the reticuloendothelial system or lymphoreticular system). The mononuclear phagocytic system is part of the organism's immune system. The histiocyt ...

which may be hemo

phagocytic Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is c ...

. Sinus hyperplasia may be associated with non-hematolymphoid malignancy. Other features include presence of white spaces and lymphocytes (large cells) within sinuses.

Complications

It is one common source of

appendicitis Appendicitis is inflammation of the appendix. Symptoms commonly include right lower abdominal pain, nausea, vomiting, and decreased appetite. However, approximately 40% of people do not have these typical symptoms. Severe complications of a ru ...

, as it may cause an obstruction of the appendiceal lumen, resulting in the subsequent filling of the appendix with mucus, causing it to distend and internal pressure to increase. Other rare case reports describe upper airway obstruction and systemic autoimmune disease.

References

{{reflist Lymphocytic disorders