Differential Diagnosis for 13-year-old with Thigh Pain

Given the laboratory results and the presentation of thigh pain in a 13-year-old, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Growing Pains: This condition is common in adolescents and is characterized by recurrent pain in the legs, typically in the thighs, calves, or behind the knees. The pain often occurs at night and can be bilateral. The normal laboratory results, including a normal complete metabolic panel (CMP), calcium level, total protein, albumin, and complete blood count (CBC), along with an elevated alkaline phosphatase (alk phos) which can be seen in growing children due to bone growth, support this diagnosis.

• Other Likely Diagnoses

  • Osgood-Schlatter Disease: A common cause of knee pain in adolescents, but it can also refer pain to the thigh. It's characterized by inflammation of the patellar ligament at the tibial tubercle and is associated with growth spurts.
  • Stress Fractures: Although less common in this age group without a history of intense athletic activity, stress fractures can occur and cause thigh pain. The normal labs do not specifically rule out this condition, but it would be less likely without a history of increased physical activity.
  • Muscle Strain: Overuse or direct injury to the muscles in the thigh can cause pain. This diagnosis is plausible given the age and potential for physical activity, but the lack of specific trauma history makes it less certain.

• Do Not Miss Diagnoses

  • Osteosarcoma: Although rare, osteosarcoma is a malignant bone tumor that can present with pain in the affected bone, which could be the thigh. It's crucial to consider this diagnosis, especially if the pain is persistent, worsening, or accompanied by other systemic symptoms like weight loss or fever, despite the normal labs.
  • Ewing's Sarcoma: Another rare malignant bone tumor that can cause pain and swelling in the affected area. Early diagnosis is critical, and any persistent or severe thigh pain in a child warrants further investigation.
  • Leukemia: Certain types of leukemia can cause bone pain due to marrow infiltration. Although the CBC is reported as within normal limits, leukemia can sometimes present with normal or near-normal blood counts early in the disease.

• Rare Diagnoses

  • Fibrous Dysplasia: A condition where normal bone is replaced with fibrous tissue, leading to weakened bones and potential for pain.
  • Gaucher's Disease: A genetic disorder that can lead to bone pain among other symptoms due to the accumulation of glucocerebroside in cells and certain organs.
  • Hypertrophic Osteoarthropathy: A rare condition characterized by clubbing of the fingers and toes, and new bone formation, which can cause pain in the long bones, including the thighs.

Each of these diagnoses has a different level of likelihood based on the provided information, but considering the age of the patient and the nature of the complaint, a thorough evaluation is necessary to rule out more serious conditions.