Gallstones Mercedes-Benz sign

Kessi Eric MC, Dokal ID, Safaa C, Youssef O and Rachida L

Published on: 2022-12-23

Abstract

The presence of gas in the fissures of gallstones is a well-known phenomenon. It is not very frequent, but when it occurs, it is characteristic and indicates the presence of one or several stones. The characteristic tri-radial arrangement of these cracks produces the  Mercedes-Benz  sign first described on an abdominal radiography by Meyers in 1973. This article is a case report of a patient followed for a left cervico-endocrine paraganglioma operated, loss of sight and who returns with an altered general state, chronic diarrhea and otalgia.

Keywords

Gallstones, Gas, Mercedes-Benz, CT Scan

Clinical Image

We report the case in a 58-year-old female patient treated in 2017 for a left cervical paraganglioma. She consulted after 5 years for an alteration of her general condition, chronic diarrhea, and otalgia. A CT scan was ordered as part of the workup and revealed a thin-walled, multi-lithiasis gallbladder with gas in it, which was discovered incidentally. The presence of gas inside the gallbladder is due to the appearance of intra lithiasis cracks in the crystallization process (Figure 1) ; about half of the stones are fissured but some of them rarely contain gas inside and mostly liquid [1-3]. The typical tri-radial distribution of gas in gallstones produces the Mercedes-Benz sign (Figure 2). This radiological sign is an important tool for the diagnosis because its presence allows to presume the existence of gallstones [1,5]. The identification of the gas image with its characteristics is therefore of great importance; on abdominal X-rays, gas can be confused with fecal matter mixed with gas from the intestinal tract; on CT, most of these signs are easily detected [4,5]. The Mercedes-Benz sign is important to know in some cases especially when gallstones and bile are isodense on CT [2]. Although the presence of the Mercedes-Benz sign allows us to presume gallstones in most cases, differential diagnoses such as aerobilia, biliary-digestive fistula and emphysematous cholecystitis must be considered [5,6].

Figure 1: Abdominal CT scan in axial section showing gas inside the gallbladder with intralithiasis fissures.

Figure 2: Abdominal CT axial section: presence of gas inside the gallbladder with a triradial arrangement characteristic of the Mercedes-Benz sign.

References

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