A patient with constant thigh pain and a mass excised from their femur most likely has what diagnosis?

The diagnosis of chondrosarcoma is supported by several factors related to the presentation of constant thigh pain and the presence of a mass excised from the femur. Chondrosarcoma is a type of bone cancer that is characterized by the production of cartilage and typically occurs in the long bones, including the femur. Patients often experience gradual onset pain, which can be exacerbated by activity or can occur at rest, reflecting the insidious nature of this tumor.

The nature of the mass is also indicative; chondrosarcomas usually present as a well-circumscribed mass that can be identified on imaging studies, often leading to surgical excision. The demographic profile, where these tumors are more common in adults rather than children, also aligns with the typical patient population encountered.

Differentiating from other conditions, while osteosarcoma usually presents with more aggressive and rapidly growing lesions that occur more commonly in adolescents and young adults, Ewing sarcoma typically affects younger individuals and may involve varying symptoms including systemic signs. Atypical stress fractures, while possible, are less likely to present as a discrete mass requiring excision and are usually associated with antecedent history of repetitive stress rather than the growth of a tumor-like mass.