Diphallia, penile duplication (PD), diphallic terata, or diphallasparatus, is an extremely rare

developmental abnormality A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can r ...

in which a male is born with two

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males d ...

es. The first reported case was by

Johannes Jacob Wecker Johannes Jacob Wecker (1528–1586) was a Swiss physician and philosopher. He worked as a doctor from 1566 and wrote a number of works about medicine, some of which were in both French and Latin. Doubtless fleeing accusations of Magic (paranorma ...

in 1609. Its occurrence is 1 in 5.5 million boys in the United States. When diphallia is present, it is usually accompanied by

renal The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...

hindgut The hindgut (or epigaster) is the posterior ( caudal) part of the alimentary canal. In mammals, it includes the distal one third of the transverse colon and the splenic flexure, the descending colon, sigmoid colon and up to the ano-rectal ju ...

anorectal Anorectal anomalies are congenital malformations of the anus and rectum. One anal anomaly, imperforate anus has an estimated incidence of 1 in 5000 births.MedLine Plus.Imperforate anus" Retrieved 13 July 2005. It affects boys and girls with simi ...

or other

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

anomalies. There is also a higher risk of

spina bifida Spina bifida (Latin for 'split spine'; SB) is a birth defect in which there is incomplete closing of the spine and the membranes around the spinal cord during early development in pregnancy. There are three main types: spina bifida occulta, men ...

. Infants born with PD and its related conditions have a higher death rate from various infections associated with their more complex renal or colorectal systems. It is thought diphallia occurs in the

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

between the 23rd and 25th days of

gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pr ...

when an injury, chemical stress, or malfunctioning

homeobox A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full-g ...

genes hamper proper function of the

caudal cell mass In humans and other mammals, the caudal cell mass (also tail bud or caudal eminence in humans) is the aggregate of undifferentiated cells at the caudal end on the spine. The caudal end of the spinal cord first begins to form after primary neurulat ...

of the fetal

mesoderm The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical Emb ...

as the

urogenital sinus The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh w ...

separates from the

genital tubercle A genital tubercle or phallic tubercle is a body of tissue present in the development of the reproductive system. It forms in the ventral, caudal region of mammalian embryos of both sexes, and eventually develops into a primordial phallus. In t ...

and

rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the l ...

to form the penis. The first case was reported by Wecker in Bologna, Italy, in 1609, and since then, about one hundred cases have been reported. This condition has existed in humans since ancient times. The two external genitalia may vary in size and shape, either lying beside each other in a

sagittal The sagittal plane (; also known as the longitudinal plane) is an anatomical plane that divides the body into right and left sections. It is perpendicular to the transverse and coronal planes. The plane may be in the center of the body and divi ...

plane or one above the other in a

frontal Front may refer to: Arts, entertainment, and media Films * ''The Front'' (1943 film), a 1943 Soviet drama film * ''The Front'', 1976 film Music *The Front (band), an American rock band signed to Columbia Records and active in the 1980s and ea ...

plane. According to Schneider classification in 1928, double penis is classified into three groups: (a) glans diphallia, (b) bifid diphallia and (c) complete diphallia or double penis. According to Vilanora and Raventos, in 1954, a fourth group called pseudodiphallia is added. The current widely accepted classification, introduced by Aleem in 1972, classifies double penis into two groups: true diphallia and bifid phallus. True diphallia is caused by cleavage of pubic tubercle; bifid phallus is caused by separation of

pubic tubercle The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis. Structure The pubic tubercle is a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of the ...

. Each of these two groups is further subdivided into partial or complete. True diphallia is where each phallus has two corpora cavernosa and a single

corpus spongiosum The corpus spongiosum is the mass of spongy tissue surrounding the male urethra within the penis. It is also called the corpus cavernosum urethrae in older texts. Anatomy The proximal part of the corpus spongiosum is expanded to form the ure ...

containing a urethra. True diphallia can be either complete with both penises similar in size, or partial when one of the phallia is smaller in size or immature, though structurally same as the larger phallus. In bifid phallus, each phallus has only one corpus cavernosum and one corpus spongiosum containing a urethra. Separation of penises down to the base of the penile shaft is complete bifid, whereas to glans is partial bifid. For complete bifid phallus associated with anomalies, the anterior urethra is absent from each penis and the

prostatic urethra The prostatic urethra, the widest and most dilatable part of the urethra canal, is about 3 cm long. It runs almost vertically through the prostate from its base to its apex, lying nearer its anterior than its posterior surface; the form of ...

is situated in the skin between the two penises. In partial bifid phallus, the duplication of urethra, corpora cavernous and corpus spongiosum in one penis is incomplete, and there is only a corpus cavernosum and a spongiosum surrounding the functioning urethra in the other penis.

Notable clinical cases

Diphallia is usually accompanied by systemic anomalies; their extent varies, ranging from no associated anomaly to multiple anomalies including urogenital, gastrointestinal and musculoskeletal systems. Penile duplication also varies from a single penis with double glans to complete double penises. The meatus may be normal at tip of glans, hypospadiac, or epispadiac; the scrotum may be normal or bifid. True diphallia is more likely accompanied with associated anomalies and malformations compared with bifid phallus. Infants born with diphallia have higher death rate due to infections associated with anomalies.

Complete true diphallia with associated anomalies

A two-day-old male newborn, associated with complex genitourinary and ano-rectal malformation. He had imperforated anus,

hypospadias Hypospadias is a common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis. It is the second-most common birth abnormality of the male reproductive system, affecting ab ...

, bifid scrotum,

meatus In anatomy, a meatus (, ),'' OED'' 2nd edition, 1989, as . plural "meatus" or "meatuses",

es on both glandes, two bladders and two colons, and had normal

testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoste ...

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

s and

ureter The ureters are tubes made of smooth muscle that propel urine from the kidneys to the urinary bladder. In a human adult, the ureters are usually long and around in diameter. The ureter is lined by urothelial cells, a type of transitional epit ...

Partial true diphallia or pseudodiphallia, without associated anomalies

Partial true diphallia corresponds to pseudodiphallia. Pseudodiphallia is formed from erectile tissue only, undifferentiated and non-functional. It is independent of the normal penis and can be removed surgically without problem. This rare case was reported, based on the age of the 83-year-old man when diphallia was only detected then when he was hospitalised, and also because of the absence of other anatomical malformations. The small, immature and nonfunctional penis protruded on one side of the large, normal penis. The secondary penis had glans but without urinary meatus.

Complete bifid diphallia with associated anomalies

A 12-year-old boy, associated with bifid

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum co ...

epispadia An epispadias is a rare type of malformation in which the urethra ends, in males, in an opening on the upper aspect of the penis, and in females when the urethra develops too far anteriorly. It occurs in around 1 in 120,000 male and 1 in 500,000 ...

and pubic symphysis diastasis. He had two separate penises, similar in size and shape, each penis had an epispadia urethral meatus. He had bifid scrotum, one testicle on each side of the scrotum. A bowel loop-like structure was over the pubis region. This structure had no communication with any other structures. He had a single normal bladder and ureter.

Partial bifid diphallia without associated anomalies

A 15-year-old boy, apart from having two penises, had normal external genitalia. His two testicles were within normal scrotum and normally positioned. He had two unequal sized glans at tip of a thick penile

shaft Shaft may refer to: Rotating machine elements * Shaft (mechanical engineering), a rotating machine element used to transmit power * Line shaft, a power transmission system * Drive shaft, a shaft for transferring torque * Axle, a shaft around whi ...

, and only urinated through the larger glans. He had a patent anus, one bladder, one normal urethra, normal

gastrointestinal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The GI tract contains all the major organs of the digestive system, in humans and ...

and

genitourinary The genitourinary system, or urogenital system, are the organs of the reproductive system and the urinary system. These are grouped together because of their proximity to each other, their common embryological origin and the use of common pathw ...

systems.

Cause

Cause of diphallia is unknown, and also because its associated anomalies vary largely, it is impossible to give a simple, single explanation of its cause. But it is thought to have started from duplication of cloacal membrane in early embryonic development stages in the fetus, between third and sixth week of gestation, because normal development of cloacal folds in the fetus is complete between this time. Normal development of penis occurs with the fusion of cloacal tubercles at anterior end of urogenital sinus. Mesenchyme migrate around cloacal membrane, proliferate and expand around cloacal plate, forming a pair of cloacal folds that fuse to form genital tubercle which develops into penis. If cloacal membrane is doubled, mesenchyme will migrate and surround both cloacal membranes, leading to the formation of two pairs of cloacal folds around two cloacal membranes, resulting in formation of two genital tubercles and thus two penises. The concept of caudal duplication syndrome is used to explain the symptoms of diphallia with associated complex anomalies in lower abdomen and urinary tract. Further, as mesenchyme migrate from more than one area, failure in migration and in the fusion of mesoderm results in formation of two genital tubercles and double penises, as well as producing associated anomalies such as double bladders, double urethra, double colons and imperforated anus. Failure in proper fusion of urethral folds results in hypospadias. Failure in mesoderm cell migration results in epispadia. Diphallia is a rare abnormal external genitalia. The cause is uncertain, but most scientists agree that diphallia is a defect of genital tubercle, and occurs at about week three of gestation, when caudal cell mass of mesoderm is affected by various external environmental factors including drugs, infections and malfunctioning

homeobox genes A homeobox is a DNA sequence, around 180 base pairs long, that regulates large-scale anatomical features in the early stages of embryonic development. For instance, mutations in a homeobox may change large-scale anatomical features of the full-g ...

Treatment

Treatment is a case-by-case analysis taking into account considerations for medical and ethical reasons, and involves surgical excision of the non-functioning penis.

References

Notes

* A scientific paper of ''triphallia'' (three penises) in a marine snail was reported.() * In 2021, the first known case of a human with triphallia was recorded in Iraq.()

External links

{{Male congenital malformations of genital organs, indeterminate sex and pseudohermaphroditism Congenital disorders of male genital organs Penis Supernumerary body parts Rare diseases Intersex variations