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Herxheimer spiral on liquid‐based papanicolaou test

Herxheimer (also Herzheimer) spirals or fibrils are classically seen in the cytoplasm of spindled squamous cells in the setting of dysplasia or carcinoma. Rarely addressed in the peer-reviewed literature, cytopathology textbooks describe their occurrence in cervical and pulmonary squamous lesions. Characterized by twisted or coiled architecture, Herxheimer spirals are keratin tonofibrils which can appear basophilic or eosinophilic on Papanicolaou (Pap) stain. Our patient was a 66-year-old woman who presented with a vaginal mass that, on physical exam, invaded the rectal wall. A ThinPrep cervicovaginal Pap test demonstrated a high-grade squamous lesion with a necrotic diathesis and scattered orangeophilic squamous cells. On close examination, a spindled squamous cell was seen to have a Herxheimer spiral running the length of its taillike cytoplasm (Fig. C-1). A concurrent test for high-risk human papillomavirus was positive. It appears that Herxheimer spirals are especially well preserved on liquid-based Pap tests. While their presence is not sensitive for squamous dysplasia/carcinoma, their specificity is probably quite high. Regardless, Herxheimer spirals are evidence of keratinization and noteworthy as a form of ultrastructure that is visible by light microscopy. References