Plain X-ray is the Next Investigation
For a male patient with a well-demarcated, red, painful lesion on the thigh, plain X-ray in two planes should be performed first to exclude bone or deep tissue pathology before considering any biopsy. 1
Rationale for X-ray First
Plain radiographs are the mandatory first-line imaging for any suspected bone or deep tissue pathology presenting with a well-demarcated, red, painful lesion, as they rapidly identify bone destruction, periosteal reaction, soft tissue calcification, or gas formation 1
X-rays are rapid, inexpensive, and provide critical information about whether deeper structures are involved, which fundamentally changes management 2, 1
Pain, especially if persistent, warrants radiological assessment to exclude bone pathology such as osteomyelitis, bone tumors, or other osseous lesions that may present with overlying soft tissue changes 1
Critical Pitfall to Avoid
Never perform a punch biopsy before adequate imaging because this can contaminate tissue planes and compromise future surgical management if malignancy (such as bone sarcoma or soft tissue sarcoma) is present 2, 1
Do not assume superficial presentation means superficial disease - a red, painful lesion could represent overlying cellulitis from underlying osteomyelitis or a bone tumor breaking through the cortex 1
The biopsy tract becomes contaminated with tumor cells and must be excised with the definitive resection specimen, making improper biopsy placement a significant surgical complication 2
Algorithm After X-ray Results
If X-ray Shows Normal Findings
- Proceed to MRI to evaluate soft tissue and bone marrow if symptoms persist and no alternative diagnosis explains the presentation 1
- Consider ultrasound for superficial soft tissue assessment if deep pathology is excluded 2
If X-ray Shows Suspicious Bone Lesion
- MRI of the whole bone with adjacent joints is the next step for local staging, as it is the best modality for evaluating extent of disease 2, 1
- Refer to a specialized sarcoma center before biopsy - the biopsy should be performed by the surgeon who will do the definitive resection, or by a member of that team 2
- Multiple core needle biopsies are preferred over open biopsy when feasible 2
Why Other Options Are Incorrect
Punch biopsy (Option A) is contraindicated before imaging as it violates fundamental oncologic principles and can worsen outcomes if malignancy is present 2, 1
MRI (Option B) is premature without first obtaining plain radiographs, which are faster, cheaper, and provide essential information about bone involvement 2, 1
Ultrasound (Option D) has limited utility for initial evaluation of a painful thigh lesion where bone pathology must be excluded first, though it may have a role after X-ray if superficial soft tissue pathology is suspected 2
Additional Considerations
Document the exact location, size, and characteristics of the lesion with photography before any intervention 2
If biopsy is eventually needed, mark the biopsy tract with a small incision or ink tattoo so it can be excised during definitive surgery 2
Longitudinal incisions are mandatory for open biopsies of extremity lesions to facilitate future limb-salvage surgery 2