DP30 Lymphovascular and perineural invasion, and possibly desmoplasia, predict behaviour of high-risk cutaneous squamous cell carcinoma

Abstract

The UK Keratinocyte Cancer Collaborative (UKKCC) are collecting high-risk cutaneous squamous cell carcinomas (cSCCs) with known tumour outcomes for locoregional recurrence (LRR). Identifying cSCCs at higher risk for LRR will support optimal management. We aimed to identify patient and pathological factors associated with locoregional recurrence and metastasis. High-risk cSCC, Brigham and Women’s Hospital stage T2b/T3 – incorporating tumour diameter, depth, poor differentiation and perineural invasion (PNI) – were identified from a Scottish health board. Pathology reports were reviewed, together with clinical data. Patient factors (age and immune status) and pathological factors [PNI, lymphovascular invasion (LVI) and desmoplasia, when mentioned] were compared with tumour outcomes. In total, 105 primary cSCCs from 105 patients were examined (age range 54–101 years): 25 of 105 (24%) from immunocompetent and 80 of 105 (76%) from immunosuppressed patients. Fifty-three tumours (50.5%) metastasized: 17 of 25 (68%) from patients with immunosuppression and 38 of 80 (45%) from immunocompetent patients (P = 0.04). PNI was reported in 35 of 105 tumours (33.3%), from which 28 of 35 (80%) were metastatic, compared with 25 of 70 from tumours without PNI (P < 0.001). Eight of 9 SCCs (89%) with LVI were metastatic, compared with 45 of 96 (47%) without LVI (P = 0.03). Desmoplasia was identified in 5 of 105 tumours (three metastatic) (P < 0.99 for desmoplasia vs. no desmoplasia). These data have been submitted to a regional meeting. LVI and PNI, and possibly desmoplasia, are associated with LRR in univariate analysis of pT3/T2b cSCC. This cohort, together with additional cases from multiple centres, are being reviewed by the UKKCC dermatopathologist panel. A comprehensive system to assess traditional risk factors (diameter, depth of invasion, histological subtype, grade, PNI and LVI), together with less well-established features (stromal desmoplasia, pattern of invasive front, maximal tumour budding and inflammatory infiltrate), is being undertaken to determine which features may have independent predictive value. It appears that desmoplasia, as defined by the expert review panel, is under-reported in cSCC. The expert panel has recorded desmoplasia in 35% of high-risk cSCCs examined to date, 78% of which have documented LRR. We suggest that cSCCs with LVI, PNI or desmoplasia warrant referral for multidisciplinary team discussion.