Case series of lipid accumulation in the human corpus cavernosum

Abstract

Erectile dysfunction is a prevalent problem affecting millions of men in the United States and around the world. There have been no reports of the presence of lipids within the human penile corporal bodies, whether in normal or diseased states. We present here a case series of 9 patients who underwent penile corporal tissue biopsy during penile prosthesis insertion with severe intracorporal fibrosis and difficulties during insertion.Oil Red O staining was done to identify lipids; LipidTOX and phalloidin double staining was used to identify lipid location within the corpora, and Masson's trichrome staining was done to assess fibrosis.We identified lipid accumulation in those 9 corporal tissue samples, and further analysis showed the distribution to be 10% intramyocellular lipids and 90% extramyocellular lipids. These 9 specimens contained increased amount of collagen when compared with controls. In addition, we analyzed corporal samples from 10 random erectile dysfunction patients presenting for penile prosthesis insertion and identified no lipid accumulation in those control patients.This is the first report of lipid accumulation in the human corpus cavernosum. Possible mechanisms of lipid accumulation include androgen deficiency and dedifferentiation of corpus smooth muscle cells into other phenotypes; however, the exact mechanism is unknown and further research is needed.

FIGURE 1

Oil Red O staining of corpus cavernosum from 3 different patients. The lipid droplets within the corpus cavernosum were conspicuous.

FIGURE 2

Lipid accumulation in human penis. In the control human penile tissue, there is no lipid (upper panel). The lipids (red, LipTOX) were distributed in 2 areas: without penile smooth muscle (middle panel) and with penile muscle (lower panel), represented as EMCL and IMCL, respectively (5.2 ± 1.3%) (original ×200). EMCL = extramyocellular lipid, IMCL = intramyocellular lipid.

FIGURE 3

Localization of lipid within the corpus cavernosum. No lipids are seen in the control corpus cavernosum tissue (left panel). Lipid droplets were readily identified in our patients’ sections. Although most lipid droplets were EMCLs located in the interstitium outside the penile smooth muscle cells (EMCLs) (90%) (middle panel), some lipid droplets were IMCLs (10%) (right panel) (original ×800). EMCL = extramyocellular lipid, IMCL = intramyocellular lipid.

FIGURE 4

Smooth muscle contents in corpus cavernosum assayed with Masson's trichrome staining. Smooth muscle manifested as red, connective tissue was green. The amount of collagen is higher in the patient group with lipid accumulation (52.8 ± 9.6%) than in the control group (5.8 ± 0.67%) (P < 0.0001) (original ×100).