Cutaneous squamous cell carcinoma of the eyelid in northern latitudes, a 25-year experience in Finland.

Purpose: To evaluate the incidence, clinical features, diagnostic challenges, management and prognosis of cutaneous squamous cell carcinoma of the eyelid (ecSCC) in southern Finland, northern Europe, latitude 62° N.

Methods: Patients were identified from the Finnish Cancer Registry and the Helsinki University Hospital databases during a 25-year period (1998-2022). Age, sex, location, clinical and histopathological diagnosis, treatment and outcome were retrieved.

Results: Cutaneous squamous cell carcinoma of the eyelid (ecSCC) was diagnosed in 58 patients. The mean age-standardized incidence was 1.03 per 100 000. Median age at the time of histopathological diagnosis was 79 (range 55-93) years; sex ratio was 0.52. Clinical diagnosis in the referral was ecSCC in only three patients. The most frequent misdiagnosis (38%) was basal cell carcinoma (BCC). One or more of the known risk factors (smoking, history of extensive sun exposure, systemic immunosuppression and previous in situ cSCC/cSCC) were documented in 71% of the patients. More than one third (38%) of the patients developed in situ SCC elsewhere on the skin; one third (31%) of the patients had invasive cSCC elsewhere. During the median follow-up time of 24 months, three patients experienced local recurrence, four patients developed metastatic disease (median 19 months) and two patients died of metastatic ecSCC.

Conclusion: The estimated incidence of ecSCC in Finland (predominantly white Caucasian) was higher than in a previous study from Europe. Clinical diagnosis of ecSCC is difficult and often misdiagnosed as BCC. Immunosuppression as a risk factor should noticed. Recurrences of ecSCC, which may be lethal, were infrequent.