Abstract
•Mitochondrial microsatellite instability (MtMSI) was found in 2 (3.5%) of 57 Keratoacanthoma (KA) patients and 8 (18.6%) of 43 cutaneous squamous cell carcinoma (SCC) patients.•In KA patients, MtMSI was detected at mitochondrial D514 D-loop in the (CA)n repeats, while all of the SCC patients presented with instabilities at D310 resulting in (C)n repeats within the D-loop region.•Our results reveal a statistically significant difference in the frequency of MtMSI between KA and SCC.•MtMSI may be a novel method for facilitating the differential diagnosis of KA and SCC.
Keratoacanthoma (KA) is a common cutaneous neoplasm which often resembles typical squamous cell carcinoma (SCC) in both its clinical and historical presentation. Several studies have attempted to identify methods for distinguishing between KA and SCC, however, none of these have proven to play any obvious roles in these tumors. Given this we went on to evaluate mitochondrial microsatellite instability (mtMSI) in KA and SCC in an effort to understand these tumors better. DNA was isolated from paired normal and tumoral tissues donated by 57 KA patients and 43 SCC patients. MtMSI was then analyzed using eight microsatellite markers and was observed in 2 (3.5%) of the 57 KA patients and 8 (18.6%) of the 43 SCC patients, respectively. MtMSI was also shown to affect different locations depending on tumor type. In KA patients, mtMSI was detected at mitochondrial D514 D-loop and presented with (CA) n repeats, in contrast, all of the SCC patient experienced mtMSI at the D310 with (C)n repeats of the D-loop region. These differences in location were found to be significant, which may support the hypothesis that KA and SCC have different pathogenetic pathways. Our results also suggest that mtMSI may be a candidate for developing novel differential diagnostic methods for KA and SCC.