Sarma DP, Weilbaecher TG(1990): Human os penis. Urology 35:349-350. PMID: 2108520 [PubMed – indexed for MEDLINE]
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HUMAN OS PENIS
DEB A P. SARMA, M.D., THOMAS G. WEILBAECHER, M.D.
From the Department of Pathology, Veterans, Administration Medical Center and Louisiana State University Medical Center, New Orleans, Louisiana
ABSTRACT—We report a case of human penile ossification with roentgenologic and histologic confirmation. The English literature is reviewed, and the pathogenesis of such a rare lesion is pre- sented. Penile ossification appears to be an acquired metaplastic process occurring in an area of fibrosis.
A sixty-one-year-old black man presented with a three-year history of painful ventral curvature of his penis on erection. He had a past history of urethral stricture requiring periodic dilatation. There was no history of trauma or metabolic disorder. Physical examination revealed a hard subcutaneous plaque, about 6 cm in length occupying the proximal half of the ventral surface of the penis. An opacity was noted on the penile roentgenogram. The results of the routine hematologic and chemical tests were normal. Cystoscopic examination and an intravenous urogram did not reveal any abnormality. At surgery the subcutaneous plaque in the ventral aspect of the penis extending from the midshaft to the symphysis pubis was easily excised. A dermal patch graft was placed over the excised area. The postoperative course was uneventful. The patient reported a full straight erection without pain. The excised partly bony dense fibrous tissue measured 3.5 x 1.5 X 0.5 cm. Microscopically, cancellous bone was embedded in dense collagenous tissue (Fig. 1). There was no significant inflammation.
Review of the English Literature
The probable earliest report of penile ossifi- cation was by M’Clellan in 1827.’ A fifty-two- year-old man came with upward incurvation of the penis that on erection would assume “the form of a semicircular bow with concavity upwards.” The septum of the corpora cavernosa was ossified. During excision “the ossified substance was so hard as to grate audibly against the knife, the edge of which was entirely destroyed by the operation.”
In 1899 Chetwood 2 described a postmortem specimen of ossification of corpora cavernosa obtained from a fifty-five-year-old man who was diabetic. The ossification extended from the base of the penis to the glans.
Gerster and Mandelbaum (1913)3 excised a 3.5 x 1.7 x 0.3 cm bony tissue from the dorsal side of the septum between the corpora cavernosa from a forty-nine-year-old man. After an elaborate histologic study they concluded that the penile bone had developed in the connective tissue by a process of metaplasia.
Vermooten (1933).4-4, described a nineteen- year-old man in whom a bony mass had developed in the glans penis, the site of a gun shot injury three months previously. The excised mass on microscopic examination revealed bone with bone marrow and cartilage. It appeared to be metaplastic bone formation in the site of traumatic fibrosis.
Another case of traumatic ossification of the dorsal penis of a forty-nine-year-old was described by Subramaniam.v(.1952).5 The patient was hit on the dorsum of the penis by a tennis ball twenty years previously.
Eglitis (1953)6 described ‘an unusual case of penile ossification occurring in a twenty-eight- year-old man. On microscopic examination of sections from a grossly normal penis at autopsy, there were numerous bony plates (5-8 mm long and 0.5-2 mm wide) in the subcutaneous tissue, particularly in the dorsal and lateral parts of the penis. Transition from fibrous connective tissue to bone was noted. There were no clues regarding the etiology of the ossification.
Elliot and Fischman (1962)7 excised a 2-inch- long bone from the tunica albuginea of the dorsal corpus spongiosum of a sixty-eight-year-old man. Although the man had suffered with gout, bone formation was thought to be unrelated.
The first case of congenital os penis in a hu- man was excised by Champion and Wegrzyn (1964)8 in a five-year-old boy. From birth the patient had a fixed penile curvature due to a bone in the right paraurethral region running from the ischium up to 1 cm from the corona. He also had a cleft scrotum.
In 1966 a case of penile ossification associated with squamous cell carcinoma of the penis occurring in a sixty-five-year-old man was reported by Morgan.9 Smith (1966)10 reported 3 cases of ossification in the excised plaques from 26 patients with Peyronie disease. Five single cases 11-15 of penile ossification reported since 1966 appear to be associated with Peyronie disease.
Many animals possess a penile bone called os penis, os priapi or baculum. The whale’s os penis may measure as long as 200 cm in length and 40 cm in circumference. During the process of evolution the os penis has progressively diminished in size until in some apes, it is an in- significant 10-20 mm structure. The nearest akin to man, the chimpanzee has no os penis, but only a small fragment of bone in the glans. The os penis in animals such as bear and wolf may serve to produce a rapidly erectile state for copulation. In the dog it serves as a channel for the urethra. The animals posssessing os penis have poorly developed erectile tissue; the penile bone that is typically situated in the glans is an aid to copulation. The erectile tissue in man’s penis is well developed so that the rare ossifica- tion occurring usually in the penile shaft leads to a penile curvature on erection preventing copulation. The osseous tissue found in the human penis does not appear to be a phylogenetic vestige because the bones that are seen in humans are larger than the os penises of the apes.
The os penis in humans appears to be acquired during the adult life. The single report of a congenital os penis was associated with other anomalies such as cleft scrotum.8
The ossification in the human penis appears to be a metaplastic process.3-6 The metaplasia probably takes place in a fertile soil composed of fibroblastic tissue. Various conditions such as trauma,4-5 neoplasm,9 venereal diseases,3 and most commonly Peyronie disease,10 may lead to metaplastic ossification. Metabolic diseases such as gout7 and diabetes mellitus2 have also been described in some cases of penile ossification. In our patient the ossification is entirely consistent with a metaplastic process in a ventral Peyronie plaque.
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- M’Clellan G: Ossification of the septum of the corpora cavernosa of the penis, Philadelphia Monthly J Med Surg 1: 256 (1827)
- Chetwood CH: Presentation of pathological specimen of os sified plaque of corpora cavernosa, J Cutan Genitourin Dis 17: 231 (1899).
- Gerster AG, and Mandelbaum FS: On the formation of bone in the human penis, Ann Surg 57: 896 (1913).
- Vermooten V: Metaplasia in the penis: the presence of bone, bone marrow and cartilage in the glans, N Engl J Med 209: 368 (1933).
- Subramaniam TK: Bone in the penis, J Indian Med Assoc 21: 437 (1952).
- Eglitis JA: Occurrence of bone tissue in the human penis, J Urol 70: 749 (1953).
- Elliot JP, and Fischman JL: Os penis, J Urol 88: 655 (1962).
- Champion RH, and Wegrzyn J: Congenital os penis, J Urol 91: 663 (1964).
- Morgan C: Bone formation in the penis associated with neo plasm, J Urol 96: 229 (1966).
- Smith BH: Peyronie’s disease, Am J Clin Pathol 45: 670 (1966).
- Gulati SC, Rao MS, and Radhakrishnan VV: Os penis, J Urol 112: 346 (1974).
- Guileyardo JM, and Sarma DP: Human penile ossification, Urology 20: 428 (1982).
- Mohar N: Os Penis: the plastic induration of the penis with metaplasia of fibrous connective tissue into cartilage and bone tis sue, Int J Dermatol 22: 235 (1983).
- Villani U, Leoni S, and Casolari E: Os penis, Eur Urol 10: 420 (1984).
- Wespes E, Bredael JJ, Couvreur Y, and Schulman CC: Penile ossification in man, Eur Urol 11: 71 (1985).
Reprinted from ApriI, 1990 issue UROLOGY © 1990 by Cahners PubIishing Company