This case report describes cytokeratin-derived amyloid deposits that can mimic invasive basal cell carcinoma on Mohs frozen sections. The amyloid appears as basophilic aggregates that may be misinterpreted as tumor nests, potentially leading to unnecessary additional stages. Recognition of this pitfall is essential for accurate intraoperative interpretation and avoiding over-treatment.

Cytokeratin-derived amyloid can appear as basophilic aggregates mimicking BCC tumor nests on frozen sections.

Congo red staining can help distinguish amyloid deposits from true tumor when diagnostic uncertainty exists.

Awareness of this artifact is critical to prevent unnecessary additional Mohs stages.