villonodular

Villonodular is a descriptive term used in pathology to denote a tissue pattern characterized by coexisting villous (frond-like) and nodular growth within a lesion, most often involving synovial tissue of joints or tendon sheaths. It is not a disease itself but a morphological description that helps convey the architectural features of certain proliferative processes, particularly those affecting the synovium.

In histological terms, villonodular proliferations display a combination of frond-like projections of the synovial lining (villous architecture) and nodular aggregates within the lesion. The cellular composition can be variable, with fibroblastic/stromal elements, inflammatory cells, and hemosiderin-containing macrophages in pigmented variants. When the pattern is described in the context of pigmented villonodular synovitis, the lesion may also show conspicuous iron deposition and multinucleated giant cells, contributing to its characteristic appearance.

Clinical significance lies in the use of the term as an architectural descriptor rather than a diagnosis. Recognizing a villonodular pattern can aid in differentiating certain synovial disorders and guiding further diagnostic and therapeutic decisions. The prognosis and management depend on the underlying condition associated with the pattern; for example, pigmented villonodular synovitis may be treated with synovectomy or other joint-sparing interventions, with approaches tailored to disease extent and location.

Overall, villonodular denotes a tissue architecture featuring both villous and nodular elements, most commonly described in synovial-based lesions, and serves as a descriptive rather than a stand-alone diagnostic category.