What is it about?
Ultrasound criteria for shallow T2 gallbladder carcinoma (GBC) are described. A protruded lesion without a deep hypoechoic area but with a conically thickened outermost hyperechoic layer corresponds to T1b carcinoma. In contrast, a protruded lesion with both a deep hypoechoic area and a conically thickened outermost hyperechoic layer corresponds to shallow T2 carcinoma (subserosal invasion depth ≤ 2 mm). A deep hypoechoic area represents an adenocarcinoma invading subserosa, accompanied by abundant fibrosis and lymphocytic infiltration, regardless of the characteristics of the outermost hyperechoic layer. Furthermore, the presence of a deep hypoechoic area is more significant than a thinned or a split outermost hyperechoic layer in diagnosing the depth of carcinoma invasion. In addition, the extension patterns differ between flat-elevated lesions and protruded lesions. The former lesion, 60-70% of early GBC, is expected to progress from A through B and C to D, while the latter lesion, 30-40%, typically progresses directly from A to D (Figure 1). In contrast, a pedunculated GBC with a thin stalk is strictly expected to be T1a.
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Why is it important?
Although simple laparoscopic cholecystectomy provides a favorable postoperative prognosis for patients with early (T1) gallbladder carcinoma (GBC), accurate differentiation between T1 and shallow T2 disease remains crucial because radical resection is associated with a favorable prognosis in patients with shallow T2 GBC. The limit of ultrasound resolution for delineating a deep hypoechoic area is generally 1-2mm. The limit of ultrasound resolution for delineating a deep hypoechoic area is generally 1–2 mm. The original authors presented cases of shallow T2 gallbladder carcinoma in which subserosal invasion was present, but no apparent deep hypoechoic area was observed because the depth of invasion was below the limit of ultrasound resolution.
Perspectives
Accurate diagnosis of T1 or shallow T2 GBC is crucial for achieving favorable treatment outcomes. Furthermore, in differentiating T1 from shallow T2 GBC on ultrasound, the presence or absence of a deep hypoechoic area suggestive of subserosal invasion is more important than thinning or splitting of the outermost hyperechoic layer.
Ph.D., M.D. Taketoshi Fujimoto
Iida Hospital
Read the Original
This page is a summary of: Ultrasound criteria for shallow T2 gallbladder carcinoma ― comment on Sugimoto M et al. a simple method for diagnosing gallbladder malignant tumors with subserosal invasion by endoscopic ultrasonography. BMC cancer. 2021; 21: 288, BMC Cancer, May 2026, Springer Science + Business Media,
DOI: 10.1186/s12885-026-16014-1.
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