Primary syphilis presenting as a painful unilateral inguinal lymphadenopathy, without cutaneous manifestations, in a 71-year-old Japanese man: A case report

Abstract

Syphilitic infection is usually observed in young patients, and the first stage of the disease (primary syphilis) is characterized by painless cutaneous and lymph node lesions. Herein, we describe a 71-year-old Japanese man with primary syphilis that presented as unilateral inguinal lymphadenopathy without skin lesions. Originally, an incarcerated hernia was clinically suspected. The lymph node pathologically showed suppurative lymphadenitis with vague granulomas; immunohistochemistry was highly suggestive of a syphilitic infection. Primary syphilis was confirmed by positive serological tests. Syphilitic infection should be included in the clinicopathological differential diagnoses for patients with inguinal lymphadenopathy, even in elderly patients without skin lesions.

Keywords: Differential diagnosis; Inguinal hernia; Lymphadenitis; Lymphadenopathy; Pathology; Syphilis.

Fig. 1

Computed tomography image of the left inguinal lymphadenopathy in a patient with primary syphilis. The left inguinal lymphadenopathy is indicated by the arrow. The soft tissue surrounding the swollen lymph nodes shows an increased density. A scale bar length is shown in the image.

Fig. 2

Microscopic findings of left inguinal lymphadenopathy in a patient with primary syphilis. Histologically, the left inguinal lymph node shows multifocal abscesses (A, areas inside the dotted lines; B, high magnification) in the central portion of the lymph node and purulent exudate (A, area indicated by arrows; C, high magnification) in the periphery. Lymphoid follicles and lymph node capsules are not evident. A multinucleated giant cell (B [arrow] and inset) is present in the abscess as is a vague granuloma (D, indicated by arrows). Perivascular localization of plasma cells is seen (E). Neutrophils are evident in the vessels, suggesting endarteritis and/or obliterative arteritis (F). (A-F) Hematoxylin and eosin staining. The lengths of the scale bars are shown.

Fig. 3

Immunohistochemical findings of left inguinal lymphadenopathy in a patient with primary syphilis. Immunohistochemistry with anti-Treponema pallidum antibodies (A-C) shows that positive-staining microorganisms are present, particularly in the lymph node cortex that also shows vascular proliferation. Spiral microorganisms are present in the wall and around the proliferating vessels (B, higher magnification of A; C, highest magnification). The lengths of the scale bars are shown.