Metastatic Workup for Squamous Cell Carcinoma of the Forearm
For SCC of the forearm, perform a thorough regional lymph node examination (epitrochlear and axillary basins) and obtain imaging only if the tumor is ≥5 cm, has high-risk pathological features, or if lymphadenopathy is present. 1
Initial Clinical Assessment
Regional lymph node examination is mandatory for all SCC cases, as nodal metastasis significantly impacts prognosis and treatment. 1 For forearm SCC, specifically palpate:
- Epitrochlear nodes
- Axillary lymph nodes bilaterally 2
Document the tumor's duration, particularly if it represents a chronic non-healing wound, and assess for immunosuppression history (HIV, organ transplantation, immunosuppressive medications). 1
Risk Stratification to Guide Workup Intensity
The extent of metastatic workup depends on identifying high-risk features:
High-risk features requiring more extensive workup include: 1, 3, 4
- Tumor size ≥2 cm (or ≥5 cm for extensive disease)
- Depth of invasion >2 mm or into subcutaneous tissue
- Poor histological differentiation
- Perineural invasion
- Recurrent tumor
- Immunosuppression
- Multiple concurrent SCC tumors
Imaging Strategy Based on Risk
For tumors ≥5 cm or those with high-risk features:
- PET-CT is the preferred comprehensive staging modality when available 2, 1
- If PET-CT unavailable, obtain CT or MRI of chest, abdomen, and pelvis to identify systemic or lymph node metastases 2
- MRI is the investigation of choice for assessing primary tumor extent, particularly involvement of underlying structures (tendons, nerves, vessels) 2, 1
For smaller, low-risk tumors (<2 cm, well-differentiated, no high-risk features):
Lymph Node Assessment Protocol
If regional lymph nodes are clinically palpable: 2, 1
- Perform ultrasound-guided fine-needle aspiration (FNA) or core-needle biopsy
- If FNA results are inconclusive after repeated attempts, proceed to surgical biopsy
- Ultrasound evaluation improves diagnostic accuracy for accessible lymph nodes 1
- If negative, no further evaluation is necessary initially, but re-examine lymph nodes every 3 months and rebiopsy if further enlargement occurs 2
Sentinel lymph node biopsy (SLNB):
- May be considered in high-risk SCC patients 2, 5
- However, there is no conclusive evidence of its prognostic or therapeutic value in changing outcomes 2, 4
- The decision should be discussed at a multidisciplinary tumor board 1, 4
Additional Workup for Symptomatic Disease
Obtain staging imaging if symptoms suggest metastatic spread: 2
- Localized bony pain → consider bone scan or PET-CT
- Deranged liver function tests → CT or MRI abdomen
- Breathlessness → CT chest
If CT scanning is unavailable, abdominal ultrasonography and/or bone scanning may help identify systemic metastases. 2
Multidisciplinary Discussion
All patients with confirmed SCC should be discussed at a multidisciplinary meeting involving dermatologist, surgeon, histopathologist, and oncologist for review of histology and planning of staging and treatment. 1, 4 This is particularly critical for tumors with high-risk features or any evidence of nodal involvement.
Common Pitfalls
- Do not perform elective regional lymph node dissection without proven nodal involvement, as this causes significant morbidity (lymphedema, chronic wounds) without proven benefit. 2
- Avoid over-imaging low-risk tumors, as this increases cost and false-positive findings without improving outcomes. 2, 4
- Do not rely solely on clinical examination for lymph node assessment in high-risk cases—ultrasound-guided FNA significantly improves diagnostic accuracy. 1
Follow-Up Surveillance
After initial workup and treatment, perform physical examinations including total body skin and lymph node examinations every 3-6 months for 2 years, then every 6-12 months thereafter. 2 For high-risk patients, imaging studies (CT or PET-CT) may be performed every 6-12 months even in the absence of symptoms. 2