Histological predictors of outcome for cutaneous squamous cell carcinoma in renal transplant patients: A case-control study

Background: Cutaneous squamous cell carcinoma is a significant cause of morbidity for immunosuppressed patients such as organ transplant recipients; however, histological parameters which predict the likelihood of tumor progression are typically based on general population studies in which immunosuppressed patients represent only a small fraction of cases. Objectives: To determine the histological parameters which have independent prognostic value for cutaneous squamous cell carcinoma arising in renal transplant recipients. Methods: Case-control study incorporating a retrospective blinded histological review of 70 archived specimens of cutaneous squamous cell carcinoma diagnosed in renal transplant recipients, comprising 10 cases where the tumor had progressed and 60 controls. Results: Progression was significantly associated with head and neck location, size, depth, poor histological grade, perineural invasion (including small caliber perineural invasion), lymphovascular invasion, and a desmoplastic growth pattern. Limitations: The retrospective nature and the low number of cases compared to controls. Conclusion: In immunosuppressed patients both small caliber perineural invasion and a desmoplastic growth pattern may also have prognostic significance in addition to other histological parameters already recognized in formal staging schemes.