Basosquamous Carcinoma: A Single Centre Clinicopathological Evaluation and Proposal of an Evidence-Based Protocol

Abstract

Basosquamous carcinoma (BSC) is an uncommon skin malignancy with significant invasive and metastatic potential. There are currently no clear management guidelines. This study evaluates the management and outcomes of patients diagnosed with BSC over a 7-year period. We present an evidence-based unit protocol for the management of BSC. All patients treated for BSC between 2009 and 2015 were reviewed. Data collected included patient demographics, tumour-specific information, management strategy, presence of recurrence or metastasis, and details of follow-up. 74 patients were identified, making this one of the largest cohorts of BSC patients reported. Mean age at diagnosis was 75.4 years, with a male:female ratio of 1.6:1. The most common tumour site was the head and neck (n=43, 58.1%). All tumours were graded at pT1 (n=51) or pT2 (n=23). Inadequate excision occurred in 17 patients (23%). Mean excision margins were >4mm peripherally and deep. Inadequately excised BSCs were further treated with wide local excision (n=6) or radiotherapy (n=5), or both (n=1). There were no cases of local recurrence or metastatic disease. This study demonstrates a cohort of patients with BSCs that appear less aggressive than previously reported. Current management with surgical excision appears to produce adequate results. However, an evidence-based guideline is still lacking.

Clinical and epidemiological analysis of basosquamous carcinoma: results of the multicenter study

“…It is also well established that BSC occurs more frequently in men 21 , 25 . Our study reflects similar results—male patients constituted 57%.…”

“…In contrast, desmoplastic and adenosquamous SCCs are highly infiltrative, have a high risk of local recurrence, metastasis, and death 29 . Some authors believe that BSC is a variant of BCC, whereas others have suggested that BSC behaves more aggressively like SCC 21 .…”

“…In our study most cases of primary BSC excision of pT1 and pT2 tumors have good clinical outcome with none of the patients developing disease recurrence or metastasis. Positive margin is a significant risk factor for recurrence of a disease 16 , 21 . In most cases reported inadequate excision rate was associated with facial area.…”

“…Despite benign appearance, BSC is characterized by aggressive subclinical spread with higher rates of recurrence: 12–51% for surgical excision and 4% for Mohs micrographic surgery. Moreover, BSC has a relatively high metastatic potential, estimated on 5–10% 21 , 22 .

Figure 1 Ulcerated basosquamous carcinoma of the left auricule ( A ).

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“…Initially, it was suggested that these lesions represent a collision of separate primary BCC and SCC which closely develop opposed to each other 23 , 25 . Summarization theory, which suggests that BSC is basal cell carcinoma that undergoes squamous differentiation 21 is supported by the current broad definition provided by the World Health Organization (WHO) in Classification of Tumors, that have categorized BSCs as “basal cell carcinomas that are associated with squamous differentiation”. On the other hand, National Comprehensive Cancer Network (NCCN), states that some cases of basosquamous tumors may be prognostically similar to SCC, so that clinicopathologic correlation is recommended in these cases and these patients may require different approach with respect to treatment and follow-up compared to BCC patients.…”