Predicting lymph node metastases in cutaneous squamous cell carcinoma: use of a morphological scoring system.

Background: Predicting which patients will develop nodal metastasis from cutaneous squamous cell carcinoma (cSCC) remains difficult. This study evaluates a recently described histological risk model validated for mucosal head and neck SCC (HNSCC) when applied to cutaneous tumours. In this model, morphologic variables including worst pattern of invasion, lymphocytic host response and perineural invasion were shown to predict disease recurrence, loco regional recurrence and overall survival in mucosal HNSCC.

Methods: Patients with cSCC and known metastatic spread were identified from the author's database over a 5-year period between July 2007 and July 2012. Histology specimens from the original primary tumour were separately analysed by 2 histopathologists. Scores were compared against T-Stage matched control specimens without metastatic spread.

Results: 27 patients with metastatic cSCC were identified. Scores for worst pattern of invasion (WPOI) were significantly higher in individuals with lymph node metastases (p=0.02).

Conclusions: Adverse pattern of invasion, defined as presence of small tumour islands or tumour satellites may be an independent risk factor for developing nodal metastases in cSCC. These tumours are difficult to investigate histopathologically as it is difficult to be confident the correct primary is chosen for study.