Lining-up-Phenomenon

The lining-up phenomenon is a histological or cytological feature that can be observed particularly in pathology. It describes the linear arrangement of cells, often along tissue structures such as vessels, nerves or basement membranes. This histological phenomenon is of great diagnostic importance in cutaneous T-cell lymphomas.

Occurrence of the lining-up phenomenon

• Lymphomas and leukemias: This phenomenon is observed in certain cases of malignant hematologic diseases, e.g. in cutaneous T-cell lymphomas (CTCL) or in mantle cell lymphomas. In this case, the lymphocytes arrange themselves like a string of pearls at the dermo-epidermal junction zone (basal epidermotropism). The lining-up phenomenon can already be observed in the early forms of CTCL and is considered an important diagnostic phenomenon.

Further examples:

• Neurogenic tumors: This phenomenon can also occur in peripheral nerve sheath tumors such as schwannomas or neurofibromas.
• Inflammatory processes: In inflammatory tissues, the migration of immune cells can also lead to a linear arrangement.

Pathophysiological significance

• The lining-up phenomenon is often caused by the interaction of the cells with the extracellular matrix or other structural components of the tissue. Adhesion molecules, such as integrins or cadherins, play an important role here.

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