Differential Diagnosis for Bilateral Thigh Pain and Weakness in a Middle-Aged Male on Chemotherapy
Single Most Likely Diagnosis
- Chemotherapy-induced neuropathy: This is a common side effect of certain chemotherapeutic agents, which can cause peripheral neuropathy leading to pain and weakness in the thighs.
Other Likely Diagnoses
- Steroid-induced myopathy: Prolonged use of corticosteroids, which are often used in conjunction with chemotherapy, can lead to muscle weakness, particularly in the proximal muscles like the thighs.
- Metastatic bone disease: In a patient with a known malignancy, metastases to the bones of the thighs could cause pain and weakness.
- Radiation-induced neuropathy or myopathy: If the patient has received radiation therapy to the pelvic or thigh area, this could be a contributing factor to his symptoms.
Do Not Miss Diagnoses
- Spinal cord compression: A potentially life-threatening condition that requires urgent attention, spinal cord compression can cause bilateral lower limb weakness and pain.
- Deep vein thrombosis (DVT): Chemotherapy increases the risk of DVT, which can cause pain and swelling in the affected limb.
- Osteonecrosis: Also known as avascular necrosis, this condition can be a side effect of long-term steroid use or chemotherapy and can cause severe pain in the affected bone.
Rare Diagnoses
- Inflammatory myopathies: Conditions like polymyositis or dermatomyositis can cause muscle weakness and pain, although they are less common in this context.
- Paraneoplastic syndromes: Rare neurological disorders that can occur in association with cancer, such as paraneoplastic neuropathy or myopathy.
- Vitamin deficiencies: Certain deficiencies, like vitamin B12 deficiency, can cause neuropathy or myopathy, although this would be less directly related to chemotherapy unless the patient has a specific dietary deficiency or malabsorption issue.