Introduction

More than 140 bursae of the human body have been de-scribed [1]. The clinically important bursae are the tro-chanteric, subdeltoid, ischiogluteal, pes anserina, iliop-soas, retrocalcaneal, and olecranon bursa because theyare the commonly infected ones [2]. The ischioglutealbursa is an inconstant anatomical finding located be-tween the ischial tuberosity and the gluteus maximus(Fig. 1) [2, 3]. Ischiogluteal bursitis is a rare disorder [3,4]. Especially in cancer patients, the appearance ofischiogluteal bursitis can be confusing in its clinical andradiological presentation [5]. To our knowledge the CTmorphology has not been described in the literature upto now.

We report the CT findings and the histopathologicaland cytopathological results of biopsies taken percuta-neously from an ischiogluteal bursitis mimicking a soft-tissue metastasis from a renal cell carcinoma.

Case report

A 66-year-old woman with renal cell carcinoma (pT 2,N 0, G1) of the left kidney underwent CT of the abdo-men and pelvis for tumor restaging 6 months after ne-phrectomy. The patient complained about pain overthe left buttock and in the left leg. Diagnostic CT exam-ination revealed a tumor-like lesion with a diameter of3.5 cm, adjacent to the left ischial tuberosity, which wassuspected to be a metastasis of the renal cell carcinoma(Fig. 2). The mass showed a broad irregular solid rimwith contrast enhancement and a hypodense centralarea. Lateral to the ischial tuberosity, a small accumula-tion of liquid with sharp margins was found. The bonewindow demonstrated only a slight cortical irregularity,but no osteolysis of the ischiatic bone. In local anesthe-sia, multiple biopsies were taken with a 16-gauge biopsyneedle (Urocut, TSK Laboratory, Tokyo, Japan) and a16-gauge coaxial sheath (Bard/Angiomed, Karlsruhe,Germany) from the mass under CT guidance with thepatient in a prone position. No malignant cells were de-tected. Histopathological findings showed a severe,chronic recurrent bursitis with degenerative cartilage al-teration. Cytopathology revealed no tumor cells, but un-specific inflammatory changes. Microbiology provedneither aerobe nor anaerobe germ growth in fermenta-tion broth.

Discussion

Hematogenous spread of renal cell carcinoma mainlyoccurs in the lungs, bones, liver, and brain. In this pa-tient, we found a suspicious mass lesion adjacent to theleft ischial tuberosity. The first tentative diagnosis wassoft-tissue metastasis from the renal cell carcinoma. Dif-ferential diagnoses included any kind of soft-tissue tu-mor, especially soft-tissue sarcoma and inflammatorychanges. No osteolytic or osteoplastic changes wereseen in CT. In renal cell carcinoma, the occurrence ofmetastases, which present central fibrosis due to tumor

Eur. Radiol. 8, 1140±1141 (1998) Ó Springer-Verlag 1998

EuropeanRadiology

Case report

Ischiogluteal bursitis mimicking soft-tissue metastasisfrom a renal cell carcinomaM. Völk1, J. Gmeinwieser1, H. Hanika2, Ch. Manke1, M.Strotzer1

1 Department of Radiology, University Hospital, D-93042 Regensburg, Germany2 Department of Urology, St. Josef Hospital, D-93053 Regensburg, Germany

Received 22 October 1997; Accepted 15 December 1997

Abstract. We report a case of ischiogluteal bursitismimicking a soft-tissue metastasis from a renal cellcarcinoma. A 66-year-old woman suffered from painover the left buttock 6 months after she was operatedon for renal cell carcinoma of the left kidney. CT ofthe abdomen and pelvis revealed a tumor-like lesionadjacent to the left os ischii, which was suspected tobe a soft-tissue metastasis. Percutaneous biopsy re-vealed no evidence of malignancy, but the histopa-thological diagnosis of chronic bursitis.

Key words: Bursa, ischiogluteal ± Bursitis ± Carcino-ma, renal cell ± Computer tomography ± Biopsy

Correspondence to: M.Völk

necrosis with hemorrhaging and secondary scarring, iswell known to pathologists. Therefore, inflammatory le-sions can be confused with metastases. To reach a diag-nosis, CT-guided percutaneous biopsy was performed.Histopathological and cytopathological examinationshowed no evidence of malignancy. The diagnosis of se-vere chronical bursitis with degenerative cartilage al-terations was made.

Although ischiogluteal bursitis has long been knownto man and is said to have been described in the time ofHippocrates [4], there are few reports of it in the recentliterature [4±7]. It has been described as a manifestationof gout [6]. Bursitis in the ischiogluteal region has alsobeen reported as a disorder appearing frequently inweavers, because of irritation or intermittent pressureupon the ischial tuberosities from prolonged sitting; itwas referred to as ªweaver's bottomº [6].

Only Mills et al. report about cancer patients suffer-ing from ischiogluteal bursitis [5]. The etiology of theischiogluteal bursitis in cancer patients is unknown.Mills et al. postulate that reduction of subcutaneous fatin the buttock results in repetitive trauma, which initi-ates the inflammation [5].

Ischiogluteal bursitis is a disorder characterized bypain over the center of the buttock and along the ham-string muscles of the leg. To our knowledge, the mor-phology of ischiogluteal bursitis has not been describedin the CT literature. In the reported case, it looked likea tumorous lesion with a broad, enhancing solid marginand a hypodense central area imitating central tumornecrosis. Lateral to the ischial tuberosity, a small accu-mulation of liquid with sharp margins was found. Therewas no destruction of the ischiatic bone, which is atypi-cal for a metastasis, although bony destruction can alsobe present in ischiogluteal bursitis [4]. The liquid forma-tion, probably within a recessus of the bursa, was indica-tive of bursitis.

Varma et al. reported the CT appearance of adistended trochanteric bursa in an asymptomatic cancerpatient with fluid attenuation where the wall of the bur-sa appeared to be thin [8]. They concluded that a disten-ded bursa must be recognized on imaging studies toavoid confusion with other lesions, especially in cancerpatients. In our case, however, the wall seemed to bethick and histopathology showed cartilage alterations,probably resulting from metaplasia of the bursa wall.

The most successful treatment of sterile bursitis is as-piration and filling of the bursal sac with a mixture ofdepot steroids and local analgesics [2, 5, 8]. In thereported patient, we aspirated the bursal sac and inject-ed lidocaine. Since the instillation of a local analgesic3 months ago, the patient has been symptom free.

References

1. Monro A secundus (1788) A description of all the bursae muco-sae of the human body. Elliot, Edinburgh

2. Larsson LG, Baum J (1986) The syndromes of bursitis. BullRheum Dis 36: 1±8

3. Bywaters EGL (1965) The bursae of the body. (editorial) AnnRheum Dis 24: 215±218

4. Chafetz N, Genant HK, Hoaglund FT (1982) Ischiogluteal tu-berculous bursitis with progressive bony destruction. J Can As-soc Radiol 33: 119±120

5. Mills GM, Baethge BA (1993) Ischiogluteal bursitis in cancerpatients: an infrequently recognized cause of pain. Am J ClinOncol 16: 229±231

6. Anderson CR (1974) Weaver's bottom. JAMA 228: 5657. Swartout R, Compere EL (1974) Ischiogluteal bursitis: the pain

in the arse. JAMA 227: 551±5528. Varma DGK, Parihar A, Richli WR (1993) CT appearance of

the distended trochanteric bursa. J Comput Assist Tomogr 17:141±143

M. Völk et al.: Ischiogluteal bursitis 1141

Fig.1. Schematic drawing ofthe left dorsal pelvis. Posteriorview of the region of theischiogluteal bursa (arrow)

Fig.2. Diagnostic CT finding of the mass lesion over the left osischii with the patient in a supine position (slice thickness 5 mm, in-travenous administration of contrast medium). The mass lesion(arrow) shows a broad, irregular solid rim with contrast enhance-ment and a hypodense central area