Differential Diagnosis
The patient presents with a lump on the medial aspect of the left knee, associated pins and needles sensation, and a history of twisting injury. The following differential diagnoses are considered:
- Single most likely diagnosis
- Meniscal cyst: The patient's symptoms of a lump on the medial aspect of the knee, associated with pins and needles sensation, and a history of twisting injury are consistent with a meniscal cyst. The presence of a bipartite patella on X-ray is a common finding, but the symptoms suggest a meniscal pathology.
- Other Likely diagnoses
- Medial meniscal tear: The patient's history of twisting injury and symptoms of pain and pins and needles sensation are consistent with a medial meniscal tear. The meniscal tear could be causing the lump and associated symptoms.
- Prepatellar or pes anserine bursitis: The patient's symptoms of a lump on the medial aspect of the knee and pain could be consistent with prepatellar or pes anserine bursitis, although the associated pins and needles sensation is less typical.
- Ganglion cyst: A ganglion cyst could present as a lump on the medial aspect of the knee, although the associated neurological symptoms are less common.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Osteosarcoma or other bone tumors: Although rare, bone tumors such as osteosarcoma could present with a lump on the knee and pain. It is essential to consider this diagnosis, especially if the MRI shows any suspicious findings.
- Deep vein thrombosis (DVT): The patient's symptoms of pain and swelling could be consistent with a DVT, although the presence of a lump and pins and needles sensation is less typical. It is essential to consider this diagnosis, especially if the patient has any risk factors for DVT.
- Nerve entrapment or compression: The patient's symptoms of pins and needles sensation and tingling could be consistent with nerve entrapment or compression, such as saphenous nerve entrapment.
- Rare diagnoses
- Synovial chondromatosis: This rare condition could present with a lump on the knee and pain, although it is less likely given the patient's symptoms and history.
- Pigmented villonodular synovitis (PVNS): This rare condition could present with a lump on the knee and pain, although it is less likely given the patient's symptoms and history.