Title: Oral syphilis with microscopic features suggestive of lymphoproliferative disorder: A case report
Abstract:
Background: Syphilis remains a well-known diagnostic mimic with highly variable clinical and histopathological manifestations. Oral involvement is uncommon and may present significant diagnostic difficulty, particularly when histologic features simulate lymphoproliferative disease. We report a case of oral syphilis presenting as an ulcerative lesion of the lip with unusual microscopic findings suggestive of a lymphoid neoplasm.
Case presentation: A 70-year-old male presented to the OMFS clinic with a 2-week history of a crusted lower lip ulcer and lymphadenopathy. With a provisional diagnosis of squamous cell carcinoma, an incisional biopsy was performed. Histopathological examination demonstrated a dense, diffuse subepithelial inflammatory infiltrate composed predominantly of lymphocytes and plasma cells, with focal architectural effacement. The infiltrate exhibited a sheet-like growth pattern with multinucleated, pleomorphic plasma cells, scattered large atypical lymphoid cells and increased mitotic activity, raising concern for a lymphoproliferative disorder. Focal perivascular inflammation and endothelial swelling were present in deeper areas but initially considered nonspecific. Immunohistochemical analysis revealed a mixed B- and T-cell population, polyclonal plasma cells and few scattered EBER-positive lymphoid cells. After the initial mis-diagnosis, the patient was treated with intralesional steroid injections with no success and was planned for excision of the lesion and repair with a local flap. The patient presented to A&E several weeks later with systemic symptoms. A swab obtained from the ulcerative lesion was submitted for polymerase chain reaction (PCR) analysis and was positive for Treponema pallidum. Subsequent serological investigations confirmed active syphilitic infection.
Discussion and conclusion: This case underscores the marked histopathological variability of oral syphilis and its potential to closely mimic plasma cell-rich lymphoproliferative disorders. Recognition of this diagnostic pitfall is essential for pathologists, particularly when evaluating oral ulcerative lesions with dense lymphoid infiltrates. A high index of suspicion and appropriate use of ancillary studies and serology are critical to ensure accurate diagnosis and appropriate patient management.
