Differential Diagnosis for 17 yo Male with Groin Pain, Back Pain, Leg Stiffness, and Skin Lesions
Single Most Likely Diagnosis
- Septic Arthritis or Osteomyelitis with Secondary Cellulitis: The combination of groin pain, back pain, leg stiffness worsening with activity, and the development of pustular and vesicular lesions with linear red streaking up the medial thigh, which is painful to touch and mildly swollen, suggests an infectious process. The progression from joint or bone infection to secondary cellulitis, characterized by the skin findings, makes this a highly plausible diagnosis.
Other Likely Diagnoses
- Lyme Disease: Given the presence of a rash (which could be interpreted as erythema migrans in the context of Lyme disease) and systemic symptoms like pain, Lyme disease is a consideration, especially if the patient has been exposed to ticks.
- Reactive Arthritis: This condition, previously known as Reiter's syndrome, can occur after certain bacterial infections and is characterized by arthritis, urethritis, and conjunctivitis, along with skin lesions. The patient's symptoms of groin pain, back pain, and leg stiffness, combined with the skin lesions, could fit this diagnosis if triggered by a recent infection.
- Psoriatic Arthritis: Although less common in this age group without a family history, psoriatic arthritis can present with joint pain and skin lesions (psoriasis). The linear red streaking could be a form of psoriatic lesion, but this would be less likely without other typical psoriatic skin changes.
Do Not Miss Diagnoses
- Necrotizing Fasciitis: Although rare, this condition is life-threatening and requires immediate attention. The presence of severe pain, swelling, and linear red streaking could be indicative of necrotizing fasciitis, especially if the patient shows signs of systemic illness like fever or hypotension.
- Deep Vein Thrombosis (DVT): The linear red streaking and swelling could also suggest a DVT, particularly if the patient has risk factors such as recent immobilization or family history of clotting disorders.
- Osteosarcoma or Other Bone Tumors: While rare, bone tumors can cause pain that worsens with activity and could potentially be associated with skin changes if the tumor has eroded through the skin or caused secondary infection.
Rare Diagnoses
- Ehlers-Danlos Syndrome: This group of disorders affects connective tissues supporting the skin, bones, blood vessels, and many other organs and tissues. Although rare, it could potentially explain some of the patient's symptoms, especially if there's a family history.
- Sarcoidosis: A condition characterized by the growth of granulomas (inflammatory cells) in various parts of the body, which could potentially cause the patient's symptoms, including skin lesions and joint pain, though it would be uncommon in this presentation and age group.