The term Vulvar intraepithelial neoplasia (VIN) refers to particular changes that can occur in the skin that covers the vulva. VIN is not cancer, and in some women it disappears without treatment. If the changes become more severe, there is a chance that cancer might develop after many years, and so it is referred to as a precancerous condition.

Peyronie's disease is a connective tissue disorder involving the growth of fibrous plaques in the soft tissue of the penis. Specifically, scar tissue forms in the tunica albuginea, the thick sheath of tissue surrounding the corpora cavernosa, causing pain, abnormal curvature, erectile dysfunction, indentation, loss of girth and shortening. A variety of treatments have been used, but none have been especially effective.

It is estimated to affect about 10% of men. The condition becomes more common with age.

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.

Medically speaking, the term denotes a squamous intraepithelial lesion of the vulva that shows dysplasia with varying degrees of atypia. The epithelial basement membrane is intact and the lesion is thus not invasive but has invasive potential.

The terminology of VIN evolved over several decades. In 1989 the Committee on Terminology, International Society for the Study of Vulvar Disease (ISSVD) replaced older terminology such as vulvar , Bowen's disease, and Kraurosis vulvae by a new classification system for "Epithelial Vulvar Disease":

- Nonneoplastic epithelial disorders of vulva and mucosa:

- Lichen sclerosus

- Squamous hyperplasia

- Other dermatoses

- Mixed neoplastic and nonneoplastic disorders

- Intraepithelial neoplasia

- Squamous vulvar intraepithelial neoplasia (VIN)

- VIN I, mildest form

- VIN II, intermediate

- VIN III, most severe form including carcinoma in situ of the vulva

- Non-squamous intraepithelial neoplasia

- Extramammary Paget's disease

- Tumors of melanocytes, noninvasive

- Invasive disease (vulvar carcinoma)

The ISSVD further revised this classification in 2004, replacing the three-grade system with a single-grade system in which only the high-grade disease is classified as VIN.

VIN is subdivided into: (Robbins Pathological Basis of Disease, 9th Ed)

Classic vulvular intraepithelial neoplasia: associated with developing into the warty and basaloid type carcinoma. This is associated with carcinogenic genotypes of HPV and/or HPV persistence factors such as cigarette smoking or immunocompromised states.

Differentiated vulvar intraepithelial neoplasia also known as VIN Simplex: is associated with vulvar dermatoses such as lichen sclerosus. It is associated with atypia of the squamous epithelium.

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.

Aphallia is a congenital malformation in which the phallus (penis or clitoris) is absent. It is the female counterpart of penile agenesis and testicular agenesis. The word is derived from the Greek "a-" for "not", and "phallos" for "penis". It is classified as an intersex condition.

Most cases involve a small and bifid penis, which requires surgical closure soon after birth, often including a reconstruction of the urethra. Where it is part of a larger exstrophy, not only the urethra but also the bladder (bladder exstrophy) or the entire perineum (cloacal exstrophy) are open and exposed on birth, requiring closure.

Despite the similarity of name, an epispadias is not a type of hypospadias, and involves a problem with a different set of embryologic processes.

Women can also have this type of congenital malformation. Epispadias of the female may occur when the urethra develops too far anteriorly, exiting in the clitoris or even more forward. For females, this may not cause difficulty in urination but may cause problems with sexual satisfaction. Frequently, the clitoris is bifurcated at the site of urethral exit, and therefore clitoral sensation is less intense during sexual intercourse due to frequent stimulation during urination. However, with proper stimulation, using either manual or positional techniques, clitoral orgasm is definitely possible.

A certain degree of curvature of the penis is considered normal, as many men are born with this benign condition, commonly referred to as congenital curvature.

The disease may cause pain; hardened, big, cord-like lesions (scar tissue known as "plaques"); or abnormal curvature of the penis when erect due to chronic inflammation of the tunica albuginea (CITA). Although the popular conception of Peyronie's disease is that it always involves curvature of the penis, the scar tissue sometimes causes divots or indentations rather than curvature. The condition may also make sexual intercourse painful and/or difficult, though it is unclear whether some men report satisfactory or unsatisfactory intercourse in spite of the disorder. It can affect men of any race and age. The disorder is confined to the penis, although a substantial number of men with Peyronie's exhibit concurrent connective tissue disorders in the hand, and to a lesser degree, in the feet. About 30 percent of men with Peyronie's disease develop fibrosis in other elastic tissues of the body, such as on the hand or foot, including Dupuytren's contracture of the hand. An increased incidence in genetically related males suggests a genetic component.

Paraphimosis is usually caused by medical professionals or parents who handle the foreskin improperly: The foreskin may be retracted during penile examination, penile cleaning, urethral catheterization, or cystoscopy; if the foreskin is left retracted for a long period, some of the foreskin tissue may become edematous (swollen with fluid), which makes subsequent reduction of the foreskin difficult.

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.

Aphallia has no known cause. It is not linked to deficient hormone amounts or action, but rather to a failure of the fetal genital tubercle to form between 3 and 6 weeks after conception. The urethra of an affected child opens on the perineum.

Paraphimosis is an uncommon medical condition in which the foreskin of a penis becomes trapped behind the glans penis, and cannot be "reduced" (pulled back to its normal flaccid position covering the glans). If this condition persists for several hours or there is any sign of a lack of blood flow, paraphimosis should be treated as a medical emergency, as it can result in gangrene.

Hyperplasia (from ancient Greek ὑπέρ "huper", "over" + πλάσις "plasis", "formation"), or hypergenesis, is an increase in the amount of organic tissue that results from cell proliferation. It may lead to the gross enlargement of an organ and the term is sometimes confused with benign neoplasia or benign tumor.

Hyperplasia is a common preneoplastic response to stimulus. Microscopically, cells resemble normal cells but are increased in numbers. Sometimes cells may also be increased in size (hypertrophy). Hyperplasia is different from hypertrophy in that the adaptive cell change in hypertrophy is an increase in the "size" of cells, whereas hyperplasia involves an increase in the "number" of cells.

A bifid penis (or double penis) is a rare congenital defect where two genital tubercles develop.

Historically, males born with a bifid penis often underwent sex reassignment surgery, due to the difficulty of penile reconstruction. They were raised as girls, and often had reconstructive surgery to make them phenotypically female, coupled with female hormone replacement therapy. However, in recent years, this practice has fallen under heavy scrutiny due to both a high frequency of sexual dysfunction in gender converted children, and more advanced penile reconstruction techniques.

Many male marsupials naturally have a bifid penis, with left and right prongs that they insert into multiple vaginal canals simultaneously.

Summer penile syndrome (also known as 'Lions Mane Penis') is a seasonal pediatric medical condition characterized by redness, swelling (Edema), and itching (pruritus) of the penile skin.

A genital ulcer is located on the genital area, usually caused by a sexually transmitted disease such as genital herpes, syphilis, chancroid, or "Chlamydia trachomatis". Some other signs of having genital ulcers include enlarged lymph nodes in the groin area, or vesicular lesions, which are small, elevated sores or blisters. The syndrome may be further classified into penile ulceration and vulval ulceration for males and females respectively.

Genital ulcers are not strictly a sign of an STD. They can occur in patients with Behcet's syndrome, lupus, and some forms of rheumatoid arthritis (all non-communicable diseases). Genital tuberculosis, often caused by direct genital contact with infected sputum, can also present as genital ulcer.

Males with penile agenesis but normal testes are of otherwise normal male appearance.

Males with testicular agenesis tend not to produce the reproductive hormone 5aDHT at any stage of their lives. As a result, they tend toward prepubescent appearance, with infantile skin texture, developing little body hair particularly in the crotch area, even vellus hair. Without genitalia of either sex, the perineum is therefore left smooth. Also muscular development is retarded and testicular agenetics are of rather frail build with short limbs and small hands and feet.

However certain male features are results of other male gender-marker hormones, "androgens", which develop male secondary sex characteristics, among which features are the deepening of the voice and facial hair.

Of the abnormal conditions associated with micropenis, most are conditions of reduced prenatal androgen production or effect, such as abnormal testicular development (testicular dysgenesis), Klinefelter syndrome, Leydig cell hypoplasia), specific defects of testosterone or dihydrotestosterone synthesis (17,20-lyase deficiency, 5α-reductase deficiency), androgen insensitivity syndromes, inadequate pituitary stimulation (gonadotropin deficiency), and other forms of congenital hypogonadism. Micropenis can also occur as part of many genetic malformation syndromes that do not involve the sex chromosomes. It is sometimes a sign of congenital growth-hormone deficiency or congenital hypopituitarism. Several homeobox genes affect penis and digit size without detectable hormone abnormalities.

In addition, in utero exposure to some estrogen based fertility drugs like diethylstilbestrol (DES) has been linked to genital abnormalities and/or a smaller than normal penis.

After evaluation to detect any of the conditions described above, micropenis can often be treated in infancy with injections of various hormones, such as human chorionic gonadotropin and testosterone.

Most eight- to fourteen-year-old boys referred for micropenis do not have the micropenis condition. Such concerns are usually explained by one of the following:

- a penis concealed in suprapubic fat (extra fat around the mons pubis)

- a large body and frame for which a prepubertal penis simply appears too small

- delayed puberty with every reason to expect good future growth

Penile torsion is a fairly common congenital condition with male infants. It occurs up to about 1 in 80 newborn males. With this condition, the penis appears rotated on its axis, almost always to the left (counterclockwise).

Examples of functional problems of the reproductive system include:

- Impotence - The inability of a male to produce or maintain an erection.

- Hypogonadism - A lack of function of the gonads, in regards to either hormones or gamete production.

- Ectopic pregnancy - When a fertilized ovum is implanted in any tissue other than the uterine wall.

- Hypoactive sexual desire disorder - A low level of sexual desire and interest.

- Female sexual arousal disorder - A condition of decreased, insufficient, or absent lubrication in females during sexual activity

- Premature ejaculation - A lack of voluntary control over ejaculation.

- Dysmenorrhea - Is a medical condition of pain during menstruation that interferes with daily activities

Summer penile syndrome is usually caused by chigger bites on the penis. Majority of cases occur in the summer months, with the clothing associated with warmer weather making penis-insect contact more likely.

Hyperplasia is considered to be a physiological (normal) response to a specific stimulus, and the cells of a hyperplastic growth remain subject to normal regulatory control mechanisms. However, hyperplasia can also occur as a pathological response, if an excess of hormone or growth factor is responsible for the stimuli. Similarly to physiological hyperplasia, cells that undergo pathologic hyperplasia are controlled by growth hormones, and cease to proliferate if such stimuli are removed. This differs from neoplasia (the process underlying cancer and benign tumors), in which genetically abnormal cells manage to proliferate in a non-physiological manner which is unresponsive to normal stimuli. That being said, the effects caused by pathologic hyperplasia can provide a suitable foundation from which neoplastic cells may develop.

Sclerosing lymphangitis is a skin condition characterized by a cordlike structure encircling the coronal sulcus of the penis, or running the length of the shaft, that has been attributed to trauma during vigorous sexual play.

Nonvenereal sclerosing lymphangitis is a rare penile lesion consisting of a minimally tender, indurated cord involving the coronal sulcus and occasionally adjacent distal penile skin. This disorder most often occurs after vigorous sexual activity and resolves spontaneously.

Etiology of Sclerosing lymphangitis is unknown but has been postulated to be secondary to thrombosis of lymphatic vessels. Spontaneous recovery can occur anywhere within a couple weeks to several months.

Although it is commonly recommended the patient abstain from any sexual activitiy during the recovery, there is no evidence that this expedites recovery nor that not abstaining worsens the condition.