Lesion	Characteristic symptoms	Typical clinical appearance	Differential diagnosis
Inflammatory and papulosquamous lesions
Angiokeratomas	Asymptomatic	Red or blue papules; may appear only on the glans penis or also on the scrotum, groin, thighs, and abdominal wall	Pearly papules
Lichen nitidus	Asymptomatic	Pinhead-sized, hypopigmented papules; often extragenital	Herpes simplex virus, pearly papules
Lichen planus	Pruritus, soreness	Flat-topped, polygonal, violaceous papules; often extragenital	Secondary syphilis
Lichen sclerosus	Phimosis, painful erections, obstructive voiding, itching, pain, bleeding	Hypopigmented, thinned, phimotic prepuce; texture similar to cellophane; isolated to prepuce and glans penis	Carcinoma in situ, leukoplakia, scleroderma
Psoriasis	Pruritus	Red or salmon-colored, papulosquamous, circinate plaques that are often associated with white or silvery scales; usually systemic	Carcinoma in situ
Infectious lesions
Genital herpes	Primary disease: constitutional symptoms followed by genital vesicles Recurrent disease: prodromal local paresthesias, pruritus, burning sensation, hypersensitivity	Vesicles on an erythematous base that become a pustule before crusting over; heals without scarring; isolated to dermatome	Lichen nitidus
Human papillomavirus lesions	Asymptomatic	Exophytic, flesh-colored, warts; lobulated or irregular surface; may appear on perineum and perianal area; diagnosis confirmed by culture, DNA detection with polymerase chain reaction, or biopsy	Squamous cell carcinoma
Primary syphilis lesions	Painless	Ulcer (chancre); isolated; darkfield microscopy is needed for diagnosis	Zoon balanitis
Scabies	Pruritus that is worse at night; family members or other close contacts are affected	Genital burrows; may become superinfected and crusted; may appear on fingers Detection of mite, egg, or pellet confirms diagnosis	Psoriasis
Neoplastic lesions
Carcinoma in situ (erythroplasia of Queyrat, Bowen disease)	Pruritus, pain	Variable appearance; plaque or ulcer isolated to glans penis, prepuce, and other areas of the penis; biopsy needed for diagnosis	Psoriasis, lichen sclerosus, Zoon balanitis, invasive penile cancer, lichen planus, herpes simplex virus, syphilis, group B streptococcal balanitis, candidiasis, Reiter syndrome
Invasive squamous cell carcinoma	Delayed presentation, usually painless	Exophytic or endophytic appearance; presentation varies; local or metastatic; biopsy is needed for diagnosis	Giant condyloma (human papillomavirus)