Track: Clinical Studies

Abstract:

Despite its ubiquity and significance in the field of dermatopathology, the nature of 'reactive atypia' is poorly understood, particularly 1) the histopathologic features that are specific for 'reactive atypia,' and 2) whether benign cutaneous keratinocytic lesions with 'reactive atypia' have a more aggressive clinical course compared to their ordinary counterparts. This study aimed to: 1) distinguish the histopathologic features that characterize 'reactive atypia' in seborrheic keratosis (SK), a prototypical benign cutaneous keratinocytic lesion, and 2) determine if SKs with reactive atypia have a more aggressive clinical course compared to SKs without reactive atypia.

After IRB approval and central pathology re-review, 142 cases were included after consensus diagnosis. Follow-up clinical data were sought for all patients through a comprehensive medical-record search and patient phone calls to determine final clinical outcomes. 

SKs with reactive atypia were significantly more likely to be irritated, inflamed, as well as exhibit nuclear pleomorphism and prominent nucleoli compared to SKs without atypia. There were no significant differences in superficial epidermal mitotic activity, nuclear-to-cytoplasmic (N/C) ratio, and extent of solar elastosis between SKs with reactive atypia and those without atypia. Additionally,  no significant differences in clinical outcomes (recurrence risk, risk of malignancy development within lesion) between SKs with reactive atypia and without atypia were seen.

In conclusion, these preliminary results suggest reactive atypia in a benign cutaneous keratinocytic lesion does not portend a worse clinical outcome.