Jacob is a 32 year old male who comes to the emergency department because of a painful, sustained erection, which has lasted five hours now. Upon further questioning, Jacob tells you that he takes antidepressant medications. You immediately order a penile arterial blood gas analysis, which reveals decreased concentration of oxygen, increased concentration of carbon dioxide, and decreased arterial pH.
Next you see Tafari, a 55 year old male of African descent. Tafari is worried because he developed a lesion on the glans penis about six months ago, and it won’t go away. Upon physical examination, you notice that the lesion looks bright red and has well-defined borders. Finally, you decide to perform an excisional biopsy to remove and analyze the lesion.
Okay, based on the initial presentation, both Jacob and Tafari seem to have some form of penile condition.
Now, the penis is made of three long cylindrical bodies: the corpus spongiosum that surrounds the penile urethra, and the two corpora cavernosa that are made of erectile tissue. The corpora cavernosa are wrapped in a fibrous coat called the tunica albuginea, and each corpus cavernosum is made up of blood-filled spaces called the cavernosal spaces. These spaces are lined with endothelial cells surrounded by smooth muscle. Running down the center of each corpus cavernosum is a large artery called the deep artery, which gives off smaller arteries that supply the cavernosal spaces. Next, blood gets drained from these spaces by small emissary veins, which drain into the deep dorsal vein. This vein then carries the blood back into the systemic circulation.
Now, for your exams, some high yield penile conditions you must absolutely remember include Peyronie disease, priapism, and squamous cell carcinoma of the penis.
Let’s start with Peyronie disease, which refers to an abnormal curvature of the penis. For your exams, make sure you don’t confuse this disease with a penile fracture, where penile injury may result in rupture of the corpora cavernosa, leading to an abnormal penile curvature. In contrast, the cause of Peyronie disease is not fully understood, however, it’s thought to be associated with repeated microtrauma during sexual intercourse. This is followed by local inflammation and collagen deposition creating a fibrous plaque in the tunica albuginea.