Two of the three penile shafts were completely internal. The Lancaster University case is forcing anatomists to rethink how often these silent variants go undiagnosed.
When anatomists at Lancaster University opened the scrotum of a 78-year-old body donor during routine dissection, they found a second penis. Then a third. The donor's external anatomy had looked entirely normal. Nothing in his medical history had flagged a congenital anomaly. The two extra penile shafts were stacked inside the scrotal sac, one posteroinferior to the primary penis and a third, smaller structure beneath that.
The case, published in the Journal of Medical Case Reports in October 2024, is only the second documented instance of triphallia in the medical literature: a congenital condition in which a person is born with three distinct penile shafts. Polyphallia overall, including cases of diphallia (two penises), is reported at roughly 1 in 5 to 6 million live births. Triphallia sits at the far end of that distribution.
What makes the case clinically interesting is what was hiding. The donor, a white man in his late seventies, had bequeathed his body to Lancaster University's anatomy program for medical education. On external inspection, his genitalia appeared unremarkable. The case report, written by Lancaster anatomists, describes the two supernumerary structures as fully internal, each containing its own corpora cavernosa and glans: the erectile tissue and tip characteristic of a functional penis. The primary and secondary shafts shared a single meandering urethra; the smallest, tertiary structure had no urethra at all.
The donor had lived his entire life with three penises, and no one, not him, not any clinician who ever examined him, not any imaging study, had detected them.
That finding points to a diagnostic gap. The authors of the case report argue that occult accessory genital structures can be clinically silent for decades, which means true prevalence is almost certainly higher than the published literature suggests. A normal-appearing scrotum and penis on physical exam do not rule out supernumerary structures beneath the surface.
Why would three penises form in the first place? The authors propose an embryological origin in the genital tubercle, the small protuberance of tissue that, in early fetal development, gives rise to the penis in males and the clitoris in females. The leading hypothesis is that the tubercle triplicated at a very early stage, around the fourth to seventh week of gestation, producing three parallel shafts instead of one. The shared, winding urethra offers a clue: the case report's authors speculate that a urethra initially formed in the secondary penis and then migrated to the primary as development proceeded.
That mechanism is not settled. Triphallia has only been documented twice: the new case and a 2014 report by Jabali and Mohammed of a child with three externally visible penile shafts, classified by the Lancaster team as morphologically distinct from the cadaveric case. Two data points cannot establish a developmental rule. What they can do is expand the catalog of observed variants that embryologists use to test competing models of how the genital tubercle organizes itself.
There is a practical reason to keep paying attention. The case report flags a list of clinical risks that follow from having accessory penile tissue the patient does not know about: urinary tract infections from a tortuous or shared urethra, traumatic catheterization if a clinician threads a catheter into the wrong channel, subfertility from disrupted ejaculatory anatomy, and sexual dysfunction in any variant that alters the structure of the erectile tissue. None of these are theoretical. They are the documented risks of polyphallia in general, and the cadaveric case suggests they can remain invisible to standard care.
Imaging studies such as ultrasound and MRI can resolve what palpation cannot, but they are not part of standard urological screening for asymptomatic adults. The donors and patients who come to light are the ones whose variants cause symptoms, which biases the literature toward the loudest cases and away from the silent ones.
What to watch next: any follow-up imaging study or case series that uses cadaveric dissection to systematically survey the prevalence of internal accessory genital structures. The Lancaster case is one body. The question worth asking is how often the textbook anatomy of a single penis conceals a second or third.