X-ray is the Next Investigation
Plain radiographs in two orthogonal planes should always be the first investigation for any suspected bone or deep tissue lesion presenting as a well-demarcated, red, painful thigh lesion, before any biopsy is performed. 1
Rationale for X-ray First
The clinical presentation of a well-demarcated, red, painful lesion on the thigh requires systematic evaluation to exclude deeper pathology before any tissue sampling:
Plain X-rays are mandatory as the initial imaging study and should never be skipped, as they rapidly identify bone destruction, periosteal reaction, soft tissue calcification, or gas formation that would fundamentally change management. 2, 1
Pain, particularly if persistent, warrants radiological assessment to exclude bone pathology such as osteomyelitis, bone tumor, or other deep tissue involvement that may present with overlying skin changes. 1
Conventional radiographs in two planes are always the first imaging study for any suspected bone or deep tissue lesion, as recommended by the National Comprehensive Cancer Network and European Society for Medical Oncology. 3, 2
Why Not Punch Biopsy First
Performing punch biopsy before adequate imaging is a critical error that can contaminate tissue planes and compromise future surgical management if malignancy is present:
Biopsy should never precede imaging when there is any possibility of deeper pathology, as this fundamental principle prevents tissue contamination and allows proper surgical planning if malignancy is discovered. 1
Never assume a superficial presentation means superficial disease, as a red, painful lesion could represent overlying cellulitis from underlying osteomyelitis or a bone tumor breaking through the cortex. 1
Excision or biopsy without staging is contraindicated for all cases that present the possibility of an aggressive-benign or malignant lesion, because inadequate margins will contaminate more tissue compartments than necessary. 3, 2
Algorithmic Approach After X-ray
If X-ray shows normal findings with persistent symptoms:
- Proceed to MRI to evaluate soft tissue and bone marrow for occult pathology. 1
If X-ray shows a suspicious bone lesion:
- MRI of the whole bone with adjacent joints for local staging is mandatory. 3, 2, 1
- Referral to a specialized sarcoma center must occur before any biopsy is performed. 2, 1
If X-ray confirms only superficial soft tissue involvement:
Common Pitfalls to Avoid
Do not biopsy before imaging - this is the most critical error that can compromise oncologic outcomes. 3, 2, 1
Do not assume pain indicates only infection or inflammation - malignancy must be excluded first with appropriate imaging. 1
Do not arrange for biopsy at a non-specialized center if imaging suggests malignancy, as bone sarcomas are frequently difficult to recognize even by experienced clinicians. 2
Answer: C. X-ray