Diagnosis may include careful identification of the cause with the aid of a good patient history, swabs and cultures, and pathological examination of a biopsy.

There are many other conditions that are similar in appearance and must be ruled out before a diagnosis of erythroplakia is made (see table). Sometimes, a diagnosis is delayed for up to two weeks in order to see if the lesion spontaneously regresses on its own or if another cause can be found. Erythroplakia frequently is associated with dysplasia, and is thus a precancerous lesion.

The disease often goes undiagnosed for several years, as it is sometimes not recognized and misdiagnosed as thrush or other problems and not correctly diagnosed until the patient is referred to a specialist when the problem does not clear up.

A biopsy of the affected skin can be done to confirm diagnosis. When a biopsy is done, hyperkeratosis, atrophic epidermis, sclerosis of dermis and lymphocyte activity in dermis are histological findings associated with LS. The biopsies are also checked for signs of dysplasia.

It has been noted that clinical diagnosis of LS can be "almost unmistakable" and therefore a biopsy may not be necessary.

Treatment involves biopsy of the lesion to identify extent of dysplasia. Complete excision of the lesion is sometimes advised depending on the histopathology found in the biopsy. Even in these cases, recurrence of the erythroplakia is common and, thus, long-term monitoring is needed.

Vaccinating girls with HPV vaccine before their initial sexual contact has been claimed to reduce incidence of VIN.

Physiologic phimosis, common in males 10 years of age and younger, is normal, and does not require intervention. Non-retractile foreskin usually becomes retractable during the course of puberty.

If phimosis in older children or adults is not causing acute and severe problems, nonsurgical measures may be effective. Choice of treatment is often determined by whether circumcision is viewed as an option of last resort to be avoided or as the preferred course.

Initial treatment in adults often involves simply pulling back the foreskin and cleaning the penis.

Fordyce spots are completely benign and require no treatment. Often their presence is considered normal anatomic variance rather than a true medical condition.

Erythroplasia of Queyrat is a squamous-cell carcinoma of the glans penis (head of the penis) or inner prepuce (foreskin) in males, and the vulvae in females. It mainly occurs in uncircumcised males, over the age of 40. Erythroplasia of Queyrat may also occur on the anal mucosa or the oral mucosa.

Some sources state that this condition is synonymous with Bowen's disease, however generally speaking Bowen's disease refers to carcinoma in situ of any location on the skin such as the lower leg. Like Bowen's disease, erythroplasia of Queyrat is associated with human papillomavirus 16 and is a precursor for invasive squamous-cell carcinoma.

It is named for French dermatologist Louis Queyrat (1856-1933), who was head of the dermatology service of l'Hôpital Ricord, a venereal hospital in Paris, now Hôpital Cochin.

The most acute complication is paraphimosis. In this condition, the glans is swollen and painful, and the foreskin is immobilized by the swelling in a partially retracted position. The proximal penis is flaccid. Some studies found phimosis to be a risk factor for urinary retention and carcinoma of the penis.

The patient may have no symptoms, or local symptomatology including itching, burning, and pain.

The diagnosis is always based on a careful inspection and a targeted biopsy of a visible vulvar lesion.

The type and distribution of lesions varies among the two different types of VIN. In the Usual type VIN, seen more frequently in young patients, lesions tend to be multifocal over an otherwise normal vulvar skin. In the differentiated type VIN, usually seen in postmenopausal women, lesions tend to be isolated and are located over a skin with a vulvar dermatosis such as Lichen slerosus.

The disease can last for a considerably long time. Occasionally, "spontaneous cure" may ensue, particularly in young girls.

Lichen sclerosus is associated with a higher risk of cancer. Skin that has been scarred as a result of lichen sclerosus is more likely to develop skin cancer. Women with lichen sclerosus may develop vulvar carcinoma. Lichen sclerosus is associated with 3–7% of all cases of vulvar squamous cell carcinoma. In women, it has been reported that 33.6 times higher vulvar cancer risk is associated with LS. A study in men reported that "The reported incidence of penile carcinoma in patients with BXO is 2.6–5.8%".

Most doctors consider this a normal physiological phenomenon and advise against treatment.

When an infant is born with PSH, the most difficult management decision has often been the sex assignment, since genitalia with this degree of ambiguity do not resemble either sex very well with respect to looks or function. Many infants with PPHS have been assigned and raised as female despite presence of testes and XY chromosomes.

Nearly all parents of infants with PPSH are offered surgical reconstruction, to either further masculinize or feminize the external genitalia.

Treatment with testosterone postnatally does not close the urethra or change the malformation, but in some cases may enlarge the penis slightly.

Paraphimosis can be avoided by bringing the foreskin back into its normal, forward, non-retracted position after retraction is no longer necessary (for instance, after cleaning the glans penis or placing a Foley catheter). Phimosis (both pathologic and normal childhood physiologic forms) is a risk factor for paraphimosis; "physiologic" phimosis resolves naturally as a child matures, but it may be advisable to treat "pathologic" phimosis via long-term stretching or elective surgical techniques (such as preputioplasty to loosen the preputial orifice or circumcision to amputate the foreskin tissue partially or completely).

The foreskin responds to the application of tension to cause expansion by creating new skin cells though the process of mitosis. The tissue expansion is permanent. Non-surgical stretching of the foreskin may be used to widen a narrow, non-retractable foreskin. Stretching may be combined with the use of a steroid cream. Beaugé recommends manual stretching for young males in preference to circumcision as a treatment for non-retractile foreskin because of the preservation of sexual sensation.

Paraphimosis can often be effectively treated by manual manipulation of the swollen foreskin tissue. This involves compressing the glans and moving the foreskin back to its normal position, perhaps with the aid of a lubricant, cold compression, and local anesthesia as necessary. If this fails, the tight edematous band of tissue can be relieved surgically with a dorsal slit or circumcision. An alternative method, the Dundee technique, entails placing multiple punctures in the swollen foreskin with a fine needle, and then expressing the edema fluid by manual pressure. According to Ghory and Sharma, treatment by circumcision may be elected as "a last resort, to be performed by a urologist". Other experts recommend delaying elective circumcision until after paraphimosis has been resolved.

Webbed penis, also called penis palmatus or penoscrotal fusion, is an acquired or congenital condition in which the scrotal skin extends onto the ventral penile shaft. The penile shaft is buried in scrotum or tethered to the scrotal midline by a fold or web of skin. The urethra and erectile bodies are usually normal. Webbed penis is usually asymptomatic, but the cosmetic appearance is often unacceptable. This condition may be corrected by surgical techniques.

In the congenital form, the deformity represents an abnormality of the attachment between the penis and the scrotum; the penis, the urethra, and the remainder of the scrotum typically are normal.

Webbed penis may also be acquired (iatrogenic) after circumcision or other penile surgery, resulting from excessive removal of ventral penile skin; the penis can retract into the scrotum, resulting in secondary phimosis (trapped penis).

One procedure for webbed penis is the insertion of a subcutaneous soft silicone implant under the penile skin. The procedure was developed by urologist James J. Elist.

Bowenoid papulosis is a cutaneous condition characterized by the presence of pigmented verrucous papules on the body of the penis. They are associated with human papillomavirus, the causative agent of genital warts. The lesions have a typical dysplastic histology and are generally considered benign, although a small percentage will develop malignant characteristics.

It is considered as a pre-malignant condition. Other terms used to describe the condition are: Erythroplasia of Queyrat, Squamous cell carcinoma in situ and Bowen’s disease. The term "Bowenoid papulosis" was coined in 1977 by Kopf and Bart and is named after dermatologist John Templeton Bowen.

The term “intraepithelial neoplasia” defines a premalignant intraepithelial change.

On the vulva it is termed VIN (vulvar or vulval intraepithelial neoplasia); on the penis, PIN (penile intraepithelial neoplasia); and on or around the anus, AIN (anal intraepithelial neoplasia). The terminology has been very confusing and it is now recommended that the terms Bowen’s disease, erythroplasia of Queyrat, and bowenoid papulosis should not be used for lesions in the anogenital area. However, dermatologists still recognize a distinct clinical variant, bowenoid papulosis, characterized by discrete papules in a younger age group and a tendency for spontaneous regression. Additionally, some authorities believe that erythroplasia of Queyrat and Bowen’s disease remain useful terms in men.

A urologist may be able to diagnose the disease and suggest treatment. An ultrasound can provide conclusive evidence of Peyronie's disease, ruling out congenital curvature or other disorders.

Procedure for buried penis is the insertion of a subcutaneous soft silicone implant under the penile skin. The procedure was developed by urologist James J. Elist.

Buried penis (also known as hidden penis) is a congenital or acquired condition, in which the penis is partially or completely hidden below the surface of the skin. It can lead to obstruction of urinary stream, poor hygiene, soft tissue infection, phimosis, and inhibition of normal sexual function. Congenital causes include maldevelopment of penile shaft skin, whereas acquired conditions include morbid obesity, overlaying abdominal fat, or penile injury. Adults with a buried penis will either live with their condition or undergo weight-loss programs. However, weight-loss programs are slow and often do not "unbury" the penis; furthermore, poor hygiene from pooling of urine can lead to soft tissue infection. Patients will eventually need definitive reconstructive surgery and more urgent surgery if infection is present. Surgeons who manage this condition are either reconstructive urologic surgeons or plastic surgeons.

The condition may be treated with surgery. There are several different techniques to treat this condition. Threading a suture through the lower membrane, and then tying a tight knot around the frenulum itself is a procedure that minimises invasive action. After a few days the frenulum will weaken and eventually break apart to allow the prepuce to fully retract. Other procedures involve the cutting of the skin and require the use of sutures to help in the healing process. Stretching exercises and steroid creams may also be helpful. Alternatively, it may be treated by a reparative plastic surgery operation called a frenuloplasty, or by complete circumcision including resection of the frenulum (frenectomy).

Hygiene, in particular the regular cleaning of the glans, is generally considered sufficient to prevent infection and inflammation of the foreskin. Full retraction of the foreskin may not be possible in boys younger than about ten years and some may not be able to fully retract their foreskin for cleaning until their late teens.

The principal treatment of chordee is surgery in infancy, usually by a pediatric urologist. With chordees caused by circumcision, the preferred method of surgical treatment is a z-plasty. The preferred time for surgery is between the ages of 6 and 18 months and correction is usually successful.

Verruciform xanthoma is uncommon, with a female:male ratio of 1:1.1

Ultrasound examination is able to depict the tunica albuginea tear in the majority of cases (as a hypoechoic discontinuity in the normally echogenic tunica). In a study on 25 patients, Zare Mehrjardi et al. concluded that ultrasound is unable to find the tear just when it is located at the penile base. In their study magnetic resonance imaging (MRI) accurately diagnosed all of the tears (as a discontinuity in the normally low signal tunica on both T1- and T2-weighted sequences). They concluded that ultrasound should be considered as the initial imaging method, and MRI can be helpful in cases that ultrasound does not depict any tear but clinical suspicious for fracture is still high. In the same study, authors investigated accuracy of ultrasound and MRI for determining the tear location (mapping of fracture) in order to performing a tailored surgical repair. MRI was more accurate than ultrasound for this purpose, but ultrasound mapping was well correlated with surgical results in cases the tear was clearly visualized on ultrasound exam.