MAGNETIC RESONANCE IMAGING OF SCLEROSING LIPOGRANULOMAOF MALE GENITALIA

KOJI NISHIZAWA, TAKASHI KOBAYASHI, KEIJI OGURA, YOSHIHIRO IDE AND KAORI TOGASHIFrom the Departments of Urology and Pathology, Hamamatsu Rosai Hospital, Hamamatsu, and Department of Diagnostic and

Interventional Imageology, Graduate School of Medicine, Kyoto University, Kyoto, Japan

KEY WORDS: adipose tissue; genital neoplasms, male; sclerosis; granuloma; magnetic resonance imaging

Sclerosing lipogranuloma of the male genitalia is relativelyrare and its pathogenesis remains unclear.1 Since this lesionoften regresses spontaneously without treatment severalweeks to months after presentation, appropriate diagnosis isessential.2 We report a case in which magnetic resonanceimaging (MRI) was used to diagnose sclerosing lipogranu-loma.

CASE REPORT

A 39-year-old Japanese man presented with a painlessintrascrotal mass. Physical examination revealed a Y-shapedelastic hard mass fixed to the subcutaneous tissue, partlycircumscribing the penile shaft and extending toward theanus. The patient denied foreign body injection or injury tothe genitalia. Urinalysis, serum biochemical studies andcomplete blood count, including eosinophilic leukocyte frac-tion, were normal. Urine culture, including tuberculosis, wasnegative.

Ultrasonography showed an ill defined area of increasedechogenic in the subcutaneous tissue. Plain and contrastenhanced computerized tomography (CT) demonstrated illdefined stranding in the area of the scrotal septum, whichextended toward the perineal subdermal region just beneaththe corpus spongiosum. Diffuse thickening of the scrotal skinwas also observed. However, tissue characteristic was notclear enough on CT to yield a definitive diagnosis.

To evaluate the lesion further MRI was performed with a1.5 T. scanner. Axial T1-weighted images obtained using aspin echo technique (time to repetition/time to echo � 600/14milliseconds) revealed ill defined tissue surrounding thespermatic cord, ill defined stranding in the area of the scrotalseptum and thickening of the scrotal skin (fig. 1, A to C). Themajority of the lesion exhibited medium signal intensity onT1-weighted images and relatively low signal intensity onT2-weighted images obtained using a fast spin echo tech-nique (time to repetition/time to echo � 4,000/97 to 106milliseconds) and was well enhanced. Only the thickenedscrotal skin showed high signal intensity on T2-weightedimaging. Coronal and sagittal T2-weighted MRI demon-strated an ill defined symmetrical Y-shaped lesion situatedjust beneath the corpus spongiosum with the arms of the Ycircumscribing the penile shaft (fig. 1, D and E).

Biopsy was performed to rule out malignancy. Histopatho-logical examination revealed granulomatous inflammationcontaining numerous epithelioid histiocytes with multinucle-ate giant cells, and considerable amounts of eosinophils andlymphocytes in the edematous fibrocollagenous tissue. Somelipid droplets surrounded by giant cells were also noted in thelesion (fig. 2). Final diagnosis was sclerosing lipogranuloma.The mass regressed spontaneously without treatment 6weeks after diagnosis.

DISCUSSION

The physical findings of sclerosing lipogranuloma in themale genitalia are unique. A reported 69% of these lesions

are symmetrical Y-shaped masses and 24% are assymmetri-cal.2 It is noteworthy that many of these patients have ahistory of foreign body injection or genital injury.1 However,these cases are not always associated with such physicalfindings or history, and it is often difficult to form a definitiveAccepted for publication May 24, 2002.

FIG. 1. A, axial T1-weighted MRI reveals ill defined tissue sur-rounding spermatic cord, ill defined stranding in area of scrotalseptum and thickening of scrotal skin (arrow). All of these lesionsexhibit signal intensity similar to that of soft tissue. B, axial T2-weighted MRI demonstrates low signal intensity of lesion aroundspermatic cord and along scrotal septum (arrow). Only scrotal skinexhibits high signal, indicating edema. C, axial T1-weighted MRIafter injection of contrast medium. Entire lesion shows strong con-trast enhancement (arrow). D, coronal T2-weighted MRI revealscharacteristic shape of ill defined lesion, which is symmetricallyY-shaped and situated just beneath corpus spongiosum with arms ofY circumscribing penile shaft (arrow). E, sagittal T2-weighted MRIdemonstrates lesion extending toward anus (arrow).

FIG. 2. Epithelioid histiocytes, multinucleated giant cells (ar-rows), eosinophils and lymphocytes are seen infiltrating edematousconnective tissue. H & E, reduced from �400.

0022-5347/02/1684-1500/0 Vol. 168, 1500–1501, October 2002THE JOURNAL OF UROLOGY® Printed in U.S.A.Copyright © 2002 by AMERICAN UROLOGICAL ASSOCIATION, INC.® DOI: 10.1097/01.ju.0000030540.17484.99

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diagnosis. In fact, only 24% of these cases are treated withoutsurgery.2

In general, MRI can image tissue characteristics moreprecisely than CT. In our case MRI allowed more detailedimaging and was helpful in the diagnosis of sclerosing li-pogranuloma. The lesion predominantly exhibited low signalintensity on T2-weighted imaging and was well enhanced.The prominent low signal intensity is atypical for malignanttissue, which is known to exhibit relatively higher signalintensity on T2-weighted images. In contrast, fibrocollag-enous tissue, which was observed microscopically in thiscase, specifically demonstrates lower signal intensity on T2-weighted images compared with noncollagenous tissue.3 Al-though CT shows fibrocollagenous tissue as a relatively highdensity lesion, it is not a specific appearance. Thus, lowsignal intensity of sclerosing lipogranuloma on MRI can bean important and definitive indicator of this condition, dif-ferentiating it from malignancy. Another helpful finding is

the characteristic Y shape of the lesion displayed on coronalMRI. In addition, MRI can be performed in any section andprovides valuable structural information. Thus, MRI is auseful means to confirm clinically suspected sclerosing li-pogranuloma, and helps to avoid unnecessary surgical inter-vention.

REFERENCES

1. Matsuda, T., Shichiri, Y., Hida, S., Okada, Y., Takeuchi, H.,Nakashima, Y. et al: Eosinophilic sclerosing lipogranuloma ofthe male genitalia not caused by exogenous lipids. J Urol, 140:1021, 1988

2. Kojima, Y., Inoue, H., Adachi, Y., Ikehara, S. and Ohshima, M.:[Sclerosing lipogranuloma of the male genitalia: report of 2cases—review of 72 cases reported in Japan.] Hinyokika Kiyo,38: 93, 1992

3. Outwater, E. K., Siegelman, E. S., Talerman, A. and Dunton, C.:Ovarian fibromas and cystadenofibromas: MRI features of thefibrous component. J Magn Reson Imaging, 7: 465, 1997

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