MCL

MCL is an acronym used in several medical contexts. The two most common references are the medial collateral ligament of the knee and mantle cell lymphoma. Context usually indicates which meaning is intended.

The medial collateral ligament, or MCL, is a band on the inner side of the knee that connects the femur to the tibia. It stabilizes the knee against valgus stress and helps limit abnormal movement. MCL injuries typically occur from direct blows to the outer knee or from twisting movements during sports. Symptoms include knee pain, swelling, tenderness along the inner knee, and sometimes a sense of instability. Diagnosis is based on physical examination and may be confirmed with imaging such as an MRI. Injuries are graded I to III by severity, with I being mild and III representing a complete tear. Treatment ranges from conservative management—rest, ice, compression, elevation, nonsteroidal anti-inflammatory drugs, bracing, and physical therapy—to surgical repair or reconstruction in selected cases, especially for high-grade injuries or significant instability. Most individuals recover fully with appropriate rehabilitation, though return to sport timing varies by injury grade and demands of the activity.

Mantle cell lymphoma, or MCL, is a type of B-cell non-Hodgkin lymphoma arising from lymphoid tissue in the mantle zone of lymph nodes. It is often characterized by a translocation t(11;14) that leads to overexpression of cyclin D1, contributing to malignant cell growth. MCL commonly presents in older adults with generalized lymphadenopathy, abdominal or pelvic involvement, and sometimes splenomegaly. Diagnosis relies on tissue biopsy with immunophenotyping showing CD5 positivity and cyclin D1 overexpression, among other features. Prognosis varies, but historically it has been aggressive with median survival of a few years, though newer therapies have improved outcomes. Treatments include chemoimmunotherapy regimens, rituximab-containing protocols, and targeted agents such as BTK inhibitors; stem cell transplantation may be considered for select patients. The term MCL thus requires context to distinguish between orthopedic injury and a hematologic malignancy.