Background: Most published series of basal cell carcinomas (BCCs) do not take into account the histopathological subtype. Recent studies suggest that the nodular and superficial types could be induced by different causal factors.
Objectives: To analyse the three major subtypes of BCC with regard to sex, age and anatomical distribution.
Methods: We retrospectively included all cases of BCC diagnosed at a single centre of dermatopathology during 1967-96. The diagnosis and subtype (nodular, superficial, morphoeiform) were confirmed by two dermatopathologists. Gender, age at excision, number of tumours and location were recorded, and analysed by histopathological subtype.
Results: We recorded 13 457 cases in 10 245 patients (M/F ratio 0.92) of mean age 65 years. Of the BCCs, 78.7% were nodular, 15.1% superficial and 6.2% morphoeiform. Nodular tumours occurred at a mean age of 66.3 years, whereas superficial tumours were excised earlier (63.0 years) and more frequently in women (M/F ratio 0.96). Patients with morphoeiform BCC had a mean age of 65.8 years and were predominantly women (M/F ratio 0.73). Both nodular and morphoeiform types predominated on the head (89.6% and 94.8%), whereas the trunk was the most common location for the superficial type (45.9%). Superficial carcinomas were predominantly located on the head in women (44.8% vs. 34.7% in men), whereas they predominated on the trunk in men (49.9% vs. 42% in women). Tumours of the trunk were excised earlier than those of the face, whatever their histological subtype, in both men and women.
Conclusions: This is the largest series of BCCs in the literature, and shows striking differences in anatomical distribution, sex and mean age according to histological type. The results suggest that the tumours of the trunk, and not only those of the superficial type, could represent a particular subtype of BCC. The analysis also suggests that the hypothesis of chronic vs. intermittent sun exposure cannot be simply extrapolated to BCC. Other causal factors, such as a genetic predisposition, could be involved in the development of carcinomas located on the trunk.