Penile carcinoma presenting as inguinal bubo,masquerading as a venereal disease

Introduction

Among the many diseases which can present as inguinal bubos, sexually transmitted infections (STIs), including lymphogranuloma venereum (LGV) and chancroid, are the most common. Rarely, a bubo can be the sole presenting feature of a malignancy, leading to a diagnostic pitfall. Penile carcinoma presenting as an inguinal bubo, and mimicking an STI has been reported rarely in the literature.

Case description

A 32-year-old man from Uttar Pradesh, India was referred to us for the evaluation of genital lesions. He developed a single painful ulcer on his glans penis six months previously, which gradually increased in size. Two months later, he noticed a painful swelling in his left inguinal region which ruptured, in two to three months, to discharge intermittent serous fluid admixed with blood. In the final month he developed progressive difficulty in retracting the preputial skin. There was no history of a genital ulcer or urethral discharge. He became sexually active at the age of 20 years and admitted to having multiple unprotected homo- and heterosexual exposures with different partners, including female commercial sex workers. On examination, there was complete phimosis and the glans penis could not be visualised. Palpation revealed a woody hard mass present at the junction of proximal 2/3 and distal 1/3 of the penis. There was a warm, tender 2 × 2 cm hyperpigmented firm swelling with overlying scarring on the left inguinal region, which released mild serous discharge on being pressed (Figure 1). Perianal examination was normal. The provisional differential diagnosis included an STI, likely chancroid or LGV, and malignancy. A Gram stain and Tzanck smear from the ulcer exudate did not show any organism or multinucleated giant cells, respectively. Chlamydia serology, ELISA for HIV, VDRL and hepatitis B surface antigen tests were negative. A dorsal slit of the foreskin was performed to relieve the phimosis and the excised tissue was sent for histopathological examination, which showed features of a moderately differentiated squamous cell carcinoma (Figure 2). HPV genotyping was not performed on the tissue specimen. Fine needle aspiration cytology from the left inguinal swelling showed atypical keratinocytes. A computed tomography scan showed ulcerated thickening of the penis with necrotic inguinal lymphadenopathy. A final diagnosis of penile squamous cell carcinoma with left inguinal lymph node metastases (T1aN2M0, stage IIIb) was made. The patient was planned for distal penectomy with inguinal lymph node dissection. OPEN IN VIEWER

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Figure 2.

(a) Ulcerated epithelium characterised by keratinocytic proliferation with keratin pearls, invading the basement membrane. (Hematoxylin and eosin, 100×). (b) Multiple keratin pearls surrounded by moderately well-differentiated keratinocytes (Hematoxylin and eosin, 200×).

Discussion

Inguinal bubo is inguinal lymphadenitis with suppuration. So strong is its association with STIs that frequently these patients receive treatment for them even in the absence of supporting evidence. In LGV, the genital ulcer is transient and is often not noticed by the patient, whereas the presence of a painful genital ulcer with undermined edges and purulent base is suggestive of chancroid. The ‘pseudobubo’ of donovanosis is not due to lymphadenitis, but occurs due to subcutaneous granuloma, and the genital ulcer is painless with a red velvety base. ¹ The differential diagnosis of inguinal bubo is not restricted to STIs alone, and includes other infectious causes like tuberculosis, plague, cat-scratch disease and tularemia. ² However, unlike their venereal counterparts, a genital ulcer is usually absent and constitutional symptoms may be present. Occasionally, inguinal lymphadenopathy can also be the presenting feature of malignancies and can lead to a diagnostic dilemma. Lymphomas mimicking LGV have been described.^3,4 Interestingly, penile carcinomas presenting as inguinal buboes, mimicking a venereal disease, have been reported only rarely;^5,6 however, transformation into squamous cell carcinoma is a known, albeit uncommon, complication in a few venereal diseases like genital warts (Buschke-Lowenstein tumour) and donovanosis. Unlike our case, the previous cases report elderly men not indulging in high-risk sexual behaviour. Our patient was a young man with a history of high-risk sexual behaviour, who presented with a painful penile ulcer and an inguinal bubo. This led to a high suspicion for a venereal disease. However, the non-healing nature of the ulcer, woody hard penile mass and a two-month time-interval between the appearance of ulcer and bubo were atypical features for STIs and raised the possibility of a malignancy. Additionally, as phimosis is a known complication of both STIs and penile carcinomas, it further added to the diagnostic confusion.

This case highlights the overlapping features of genital malignancy and STIs. Presence of a firm penile mass, negative work-up for STIs and lack of response to treatment should alert the dermatologist to this rare but important cause of inguinal bubo, irrespective of the sexual history. Penile carcinoma should be included in the differential diagnosis of inguinal bubo. A high index of clinical suspicion is necessary to make an early diagnosis of penile carcinoma in such a setting.