The Histopathologic Spectrum of Syphilis: A Case Series

Summary: Background Secondary syphilis is known as "the great imitator" due to its range of clinicopathologic manifestations. Histopathologic examination may be required to prevent misdiagnosis. This case series describes secondary syphilis (n=3). Results Case 1: A 35-year-old female presented for evaluation of tender verrucous plaques involving the vulva for approximately two weeks. Biopsy demonstrated epidermal hyperplasia with dense neutrophilic and lymphoplasmacytic inflammation, consistent with condyloma lata. Treponemal stain revealed spirochetes along the dermal-epidermal junction (DEJ) and superficial vessels. Case 2: A 65-year-old male presented with urticarial patches and plaques involving the trunk and lower extremities for approximately four months. Biopsy demonstrated a dense perivascular lymphoplasmacytic infiltrate; treponemal stain revealed spirochetes surrounding superficial vessels. Case 3: A 23-year-old male presented with erythematous annular papules involving the scrotum for several years, previously treated as fungal infection. Biopsy demonstrated a dense lymphohistiocytic band; treponemal stain revealed spirochetes along the DEJ. Conclusion Secondary syphilis is characterized by histopathologic features such as endothelial swelling, irregular acanthosis, elongated rete ridges, and necrotic keratinocytes. Plasma cells are a common feature and are of historical significance. The wide spectrum of features and varying chronicity of symptoms should prompt a lower threshold for treponemal staining, especially given increasing incidence rates.