The penis consists of three tubes: the hollow urethra that carries urine and semen, and two soft, spongy tubes called the corpora cavernosa that fill with blood to stiffen the penis in an erection. All three are encased in a tough, fibrous sheath called the tunica albuginea that, when plaque forms, makes the sheath less flexible. Depending on the location of the plaque (in 70 percent of cases, it forms on the top side of the penis), it can cause the penis to bend up, down or to the side when it stiffens. Sometimes plaque forms around the penis, creating a narrow band like the neck of a bottle.

Heredity and certain connective tissue disorders like Dupuytren’s contractures increase the risk of developing Peyronie’s. Elevated blood sugar, smoking and pelvic trauma also increase the risk. The disease can develop gradually or come on suddenly. It occurs in two phases: acute and chronic. The acute phase, which often causes painful erections, lasts for six to 18 months, during which plaque forms and deformity of the erect penis worsens. In the chronic phase, the pain ends, the plaque stops growing and the deformity stabilizes.

Mr. Cummings’s doctor told him it was good that he came for treatment early, before the plaque became calcified and harder to treat. As he described it, the many injections of verapamil put holes in the plaque, “changing it from Cheddar to Swiss” and making the penis more flexible. He also spent hours a day stretching his penis with a traction device called Andropenis, an F.D.A.-approved penile extender.

This and similar devices can help lengthen a penis shortened by Peyronie’s and foster straighter remodeling as the plaque is replaced with healthy collagen.

“Xiaflex is not a miracle drug,” Dr. Mills said. “The trial that led to F.D.A. approval saw a 35 percent improvement in curvature, although we’re seeing about a 50 percent decrease. I tell patients ‘You’re never going to get back the penis you had, but you can get a functional penis,’ which is what most men want.” Only rarely does the problem correct itself without treatment.

Severe cases that don’t respond adequately to injections may be treated surgically, an option usually reserved for men with disabling deformities that make sexual activity difficult. Surgery is not done until the plaque and curvature have stabilized. Options include shortening the side of the penis opposite the curve or extending the curved side by filling in with a graft, a more challenging approach.

Some men with Peyronie’s disease who also have erectile dysfunction may be fitted with an inflatable pump or malleable silicone rods that straighten the penis and make it stiff enough for penetration.