Erythroplasia of the glans penis was first described by Queyrat in 1911. EQ affects the mucosal surfaces of the penis (glans, inner prepuce or distal urethra) and has a number of clinical presentations. Lesions can vary from patchy erythema to diffuse shiny erythema with or without erosions. EQ can also present as well-demarcated velvety plaques, which can coalesce to form a large contiguous plaque. They are often painless but can be extremely painful with the presence of erosions. Transformation into invasive carcinoma has been reported in up to 33 % of cases [9]. Histopathologically these lesions show undifferentiated PeIN.

Bowen’s disease is histologically indistinguishable from erythroplasia of Queyrat; however, it involves non-mucosal skin rather than penile mucosa. It usually presents as a single well-defined plaque of scaly erythema. The appearances can vary with ulcerated, keratotic or elevated flesh-coloured plaques described. Lesions may even become heavily pigmented and resemble melanoma. Malignant transformation has been reported in 5 % of cases [10].

Bowenoid papulosis occurs mainly in sexually active young men and is strongly associated with HPV subtype 16. It is characterised by pink, velvety papules. The papules are often multiple and can coalesce into plaques. Lesions tend to occur on the penile shaft or mons pubis where they often appear more pigmented. They are less frequently found on the glans or inner prepuce. Lesions can be pruritic but are often asymptomatic. Histologically the lesions show undifferentiated PeIN with warty features. However, it tends to run a more benign course with malignant transformation seen in less than 1 % of cases [11].

Giant condyloma accuminatum (GCA) was first described by Buschke and Lowenstein in 1925. This large, exophytic, cauliflower-like growth results from a confluence of condyloma acuminata, smaller warty growths that can affect any part of the anogenital region. On the penis these lesions tend to be found in the coronal sulcus and frenulum. They have a strong association with HPV 6 and 11. Although GCA was thought originally to be benign, the lesion is now thought to be a type of warty carcinoma, and careful examination of these lesions often shows invasion [12]. Older literature refers to GCA interchangeably as verrucous carcinoma. It is now widely accepted that GCA and verrucous carcinoma are two distinct pathologies due to the well-documented role of HPV in the pathogenesis of GCA, which is not commonly seen with verrucous carcinoma.

Verrucous hyperplasia appears as thickened pale areas of mucosa without nodularity. Histologically there is epithelial hyperplasia with elongation of broad rete ridges without cytological atypia. It is thought to be a premalignant lesion leading to verrucous carcinoma and should be excised with a narrow margin [13].

Lichen sclerosus (LS) is a chronic inflammatory skin condition of unknown aetiology. Lesions appear as white plaques on the prepuce and glans. The resulting sclerosis can cause phimosis, adherence of the prepuce to the glans, meatal stenosis and urethral strictures.

A number of studies have shown a strong association between LS and penile cancer. Several studies comment on the presence of synchronous penile cancer in LS specimens. Barbagli et al. reviewed the histology of 130 patients with male genital lichen sclerosis and reported the finding of malignant or premalignant lesions in 11 (8.4 %) of the specimens [14]. Nasca et al. reviewed the histology of 86 patients over a 10-year period, finding malignant or premalignant lesions in 5 (5.8 %) of the samples [15]. In the largest series to date, Depasquale et al. identified 12 patients with squamous cell carcinoma from 522 patients (2.3 %) treated for LS over a 14-year period [16]. Seven of these patients had been previously circumcised for LS and later developed SCC, and five had LS in uncircumcised penises. There was no reference to the inclusion of premalignant lesions in this study, which may account for the rates being lower than those reported in other series. In another smaller series, Campus et al. identified SCC in 2 of 54 patients treated for LS (3.7 %) [17].

There are also a number of studies that report the synchronous finding of LS in the histology of excised malignant and premalignant penile lesions. Velazquez and Cubilla identified synchronous LS in 68 of 207 penile SCC specimens (32.8 %) [18]. Pietrzak et al. identified synchronous LS in 44 of 105 patients with penile SCC or CIS (28 %) [19]. A recent study by Chaux et al. showed the association of LS with differentiated PeIN in 39 of 77 cases (51 %) [20]. Mannweiler investigated the association of LS with 35 patients with differentiated PeIN or HPV and p16^INK4a over-expression negative SCC. 26 (74.3 %) of these patients had synchronous LS [21].

Where patients have undergone circumcision for LS, we would advise that the prepuce is always sent for histological analysis to look for differentiated PeIN. Further follow-up depends on the extent of persistent glanular and/or urethral changes. A relatively normal-appearing glans does not require outpatient follow-up, and the patient can be advised to perform regular self-examination. If the glans is particularly inflamed, a period of topical steroid use and follow-up is advised.

Penile cutaneous horn describes a conical, protruding, hyperkeratotic mass usually arising from the glans or coronal sulcus. In most cases, there is a history of chronic inflammation and phimosis. The base of the lesion can show dysplastic changes amounting to differentiated PeIN, and these lesions may also be associated with hyperplastic lichen sclerosus.