Signet-ring cell carcinoma of the appendix: a case report with an emphasis on sonographic findings

Abstract

In this report, we present a rare case of primary signet-ring cell carcinoma of the appendix in a 51-year-old woman with right lower quadrant pain. Since non-specific concentric appendiceal wall thickening was found in a radiologic evaluation, it was misdiagnosed as non-tumorous appendicitis. An in-depth examination of the correlation between sonographic and histopathologic findings demonstrated that a single markedly thickened hypoechoic layer was well correlated with the diffuse infiltration of tumor cells in both the submucosal and muscle layers. If this sonographic finding is observed in certain clinical settings, such as potential ovarian and peritoneal metastasis, submucosal infiltrative tumors, including signet-ring cell carcinoma, should be considered in the differential diagnosis.

Keywords: Appendix; Carcinoma, signet ring cell; Ultrasonography.

Fig. 1.. A 51-year-old woman with right lower quadrant pain.

A. An axial sonogram image of the appendix shows a concentrically thickened wall with marked hypoechoic submucosal and muscle layers that are not clearly distinguishable. B. In a color Doppler examination, a well-demarcated heterogeneous echoic solid mass with a weak flow signal, approximately 4 cm in size, was found. C. A coronal computed tomography (CT) scan of the appendix shows non-specific appendiceal wall thickening with mild periappendiceal fatty strands (arrowheads). D. An enhancing solid mass was identified in the right adnexa on an axial CT scan. E. A low-power microphotograph shows asymmetrical concentric wall thickening of the appendix (H&E, ×10). Tumor cells were found diffusely infiltrating the submucosal, muscle, and serosal layers. F. Under higher magnification, signet-ring cells are seen diffusely infiltrating a muscle layer of the appendix (arrowheads) (H&E, ×100; inset, H&E, ×400). L, lumen; M, muscle; m, mucosa; S, serosa; sm, submucosa.