Imaging features of appendiceal signet ring cell carcinoma with uterine implantation: A case report

Abstract

BACKGROUND

Signet ring cell carcinoma originating from the appendix is extremely rare, and the lack of specific clinical symptoms and imaging features makes preoperative diagnosis particularly challenging.

CASE SUMMARY

We report a case of a 49-year-old woman who presented with irregular vaginal bleeding lasting more than five months. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed an enlarged appendix with a thickened wall and progressive enhancement after contrast administration. The uterine myometrium and cervix were markedly thickened, with heterogeneous density and signal intensity, along with progressive enhancement. The uterine serosal surface remained intact. Preoperative MRI suggested diffuse uterine adenomyosis; however, postoperative histopathology confirmed Signet ring cell carcinoma originating from the appendix with implantation involving the entire uterus.

CONCLUSION

Imaging showed appendiceal wall thickening and marked thickening of the uterine myometrium, with lesions demonstrating progressive enhancement after contrast administration. These findings should raise suspicion for the implantation of Signet ring cell carcinoma originating from the appendix and involving the uterus. Signet ring cell carcinoma originating from the appendix is relatively rare, and its imaging features are seldom reported, making preoperative diagnosis extremely challenging. This study retrospectively analyzes a case of Signet ring cell carcinoma originating from the appendix with implantation involving the entire uterus. The imaging characteristics of the appendix and the uterus were evaluated using CT and MRI to enhance awareness of this disease.

Key Words: Signet ring cell carcinoma; Appendix; Magnetic resonance imaging; Malignant tumor; Case report

Core Tip: Signet ring cell carcinoma originating from the appendix is relatively rare, and its imaging features are seldom reported, making preoperative diagnosis extremely challenging. This study retrospectively analyzes a case of Signet ring cell carcinoma originating from the appendix and implantation to the entire uterus. The imaging characteristics of both the appendix and the uterus were analyzed using computed tomography and magnetic resonance imaging, with the aim of enhancing awareness of this disease.

INTRODUCTION

Signet ring cell carcinoma is a distinct clinical and pathological subtype of colorectal cancer, characterized by aggressive behavior and a low incidence of approximately 0.6%-2.3%[1–6]. Signet ring cell carcinoma originating from the appendix is even rarer, accounting for about 16% of all Signet ring cell carcinoma cases[6]. Approximately 93% of appendiceal signet ring cell carcinomas have metastasized to adjacent organs, lymph nodes, or the peritoneal cavity at diagnosis[6]. Early detection and intervention are therefore essential for improving patient outcomes[7]. Accurate preoperative diagnosis remains challenging because of nonspecific clinical symptoms and a lack of characteristic imaging findings. This report presents a rare case of appendiceal Signet ring cell carcinoma with implantation to the entire uterus, emphasizing its computed tomography (CT) and magnetic resonance imaging (MRI) characteristics to improve disease recognition.

CASE PRESENTATION

Chief complaints

A 49-year-old woman presented with more than 5 months of irregular vaginal bleeding.

History of present illness

Her last menstrual period occurred on April 15, 2023, and was initially accompanied by heavy bleeding. She sought care at a local hospital and received unspecified medical therapy that reduced the bleeding; intermittent spotting persisted. She denied significant abdominal pain, dizziness, headache, palpitations, or anal fullness.

History of past illness

No notable past medical history.

Personal and family history

There was no significant personal and family history.

Physical examination

Vital signs were as follows: Temperature, 36.8 °C; heart rate, 75 beats per minute; respiratory rate, 19 breaths per min; and blood pressure, 150/82 mmHg. She was alert and appeared well, with no jaundice of the skin or sclera. Cardiopulmonary auscultation was unremarkable. The liver and spleen were not palpable below the costal margins, and there was no edema of the lower extremities.

Laboratory examinations

Laboratory results were as follows: Hemoglobin 94 g/L (reference range: 115–150 g/L); carcinoembryonic antigen 6.2 ng/mL (≤ 5 ng/mL); cancer antigen 125 60.2 U/mL (≤ 35 U/mL); cancer antigen 19-9 3.2 U/mL (≤ 37 U/mL); human epididymis protein 4 50.1 pmol/L (≤ 70 pmol/L for premenopausal women); and risk of ovarian malignancy algorithm index 8.11% (reference range for premenopausal women, 0%–7.4%.

Imaging examinations

Enhancement rate measurement method: A round region-of-interest (20-40 mm²) was set in the solid component of lesion. Plain scan CT value, arterial phase CT value, venous phase CT value and lag phase CT value were measured on the same level, and each CT value was measured three times. The means were recorded as the final results. CT enhancement rate of arterial phase: (Arterial phase CT value-plain scan CT value)/plain scan CT value. Enhancement rate of venous phase: (Venous phase CT value-plain scan CT value)/plain scan CT value. Enhancement rate of lag phase: (Lag phase CT value-plain scan CT value)/plain scan CT value[8]. The enhancement rate of lesion in MR referred to the CT measurement method. The MR enhancement rate of arterial phase: (Arterial phase MR value-plain scan MR value)/plain scan MR value. Enhancement rate of venous phase: (Venous phase MR value-plain scan MR value)/plain scan MR value. Enhancement rate of lag phase: (Lag phase MR value-plain scan MR value)/plain scan MR value.

CT findings: The appendix was enlarged with concentric wall thickening and lacked significant intraluminal gas or fecalith-like density. Following contrast administration, the appendiceal wall demonstrated gradual and progressive enhancement, with enhancement rates of 17.8% in the arterial phase, 21.4% in the venous phase, and 46.4% in the delayed phase (Figure 1A). The lesion exhibited a clear boundary from the surrounding tissues, with no evidence of exudative changes.

Figure 1 Computed tomography features of the appendix and uterus. A: Computed tomography (CT) enhanced coronal view: Coarsening appendix (arrowhead), strengthening after enhancement, clear boundary between focus and surrounding tissues; B: CT enhanced sagittal view: Obvious uterus enlargement, obvious muscular.

The uterus appeared uniformly enlarged with an uneven myometrial texture and a smooth perimetrium. It also showed continuous progressive enhancement after contrast administration (Figure 1B), with enhancement rates of 25.0% in the arterial phase, 36.8% in the venous phase, and 55.3% in the delayed phase. The uterine lesion maintained a well-defined border from adjacent structures. No obvious pelvic lymphadenopathy was observed.

MRI findings: The appendix appeared enlarged, demonstrating isointensity on T1-weighted imaging (T1WI) and slight hyperintensity on T2-weighted imaging (T2WI) (Figure 2A). Diffusion-weighted imaging (DWI) showed mildly hyperintense signals, with no significant reduction in the apparent diffusion coefficient value. After contrast administration, the lesion exhibited gradual and progressive enhancement, with enhancement rates of 35.4% in the arterial phase, 60.6% in the venous phase, and 71.6% in the delayed phase. The lesion was well demarcated from adjacent tissues.

Figure 2 Magnetic resonance imaging features of appendix and uterus. A: T2-weighted imaging (T2WI) transverse view: Coarsening appendix (arrowhead), T2WI high signal, and signals are relatively uniform; B: T2WI sagittal view, obvious thickening mesometrium (arrowhead), and ambiguous display of bonding zone; C: Diffusion-weighted imaging, the enlarged uterus presents slightly high signals; D: T1-weighted imaging enhanced sagittal view, strengthening mesometrium and relatively complete serosa.

The uterine junctional zone was indistinct, with significant thickening of the myometrium and cervix. The lesion showed isointensity on T1WI and iso- to hyperintense signals on T2WI (Figure 2B). DWI revealed mild hyperintensity (Figure 2C), and the ADC value showed no obvious reduction. Post-contrast images demonstrated gradual and progressive enhancement of the uterus and cervix (Figure 2D), with enhancement rates of 35.8% in the arterial phase, 76.6% in the venous phase, and 97.5% in the delayed phase.

Both ovaries were clearly visualized, showing no abnormal signal on DWI and no significant enhancement post-contrast. A small amount of free fluid was noted in the pelvic cavity.

CT diagnosis: Enlarged appendix noted; differential diagnosis requires further evaluation. Significant uterine enlargement with heterogeneous myometrial enhancement was observed.

MRI diagnosis: Thickened appendix; specialist consultation recommended for comprehensive assessment. Marked heterogeneous thickening of the myometrium and cervix, suggestive of diffuse adenomyosis; additional evaluation warranted. Small volume of free pelvic fluid.

Preliminary clinical diagnosis: Abnormal uterine bleeding; mild anemia; uterine adenomyosis; appendiceal tumor?

Postoperative pathological diagnosis: Appendiceal Signet ring cell carcinoma involved the entire appendix and serosa, extending into the cecal muscular layer and serosa. Signet ring cell carcinoma was identified in the endometrium, myometrium, and serosa. Signet ring cell carcinoma also involved the cervical stroma.

FINAL DIAGNOSIS

Appendiceal Signet ring cell carcinoma involved the entire appendix and serosa (Figure 3), extending into the cecal muscle layer, serosa. Signet ring cell carcinoma was identified in the endometrium, myometrium, and serosa (Figure 4). Signet ring cell carcinoma also involved the cervical stroma.

Figure 3 Intraoperative specimens and pathological images of appendix surgery. A: Intraoperative enlargement of the appendix; B: Pathological images (original magnification, × 200).

Figure 4 Intraoperative specimens and pathological images of uterine surgery. A: Intraoperative enlarged uterus; B: Pathological images (original magnification, × 400).

TREATMENT

The patient received adjuvant chemotherapy after surgery.

OUTCOME AND FOLLOW-UP

Has been followed for two years. Regular monitoring with tumor markers and imaging has revealed no evidence of recurrence, and follow-up is ongoing.

DISCUSSION

Appendiceal Signet ring cell carcinoma often presents with nonspecific clinical manifestations and may be asymptomatic or mimic acute appendicitis[7,9]. The tumor commonly causes obstruction of the appendiceal lumen, leading to increased intraluminal pressure or compression of the appendiceal mesentery. This results in ischemia, congestion, and potentially secondary bacterial infection. These pathological changes manifest as appendicitis, influenced by the appendix’s anatomical characteristics, making preoperative diagnosis extremely challenging. Therefore, histopathological evaluation after surgery is essential for accurate diagnosis[10]. Signet ring cell carcinoma is considered the histopathological subtype of gastrointestinal cancers with the poorest prognosis[11], characterized by high invasiveness and aggressive clinical behavior[12]. Alarmingly, the 5-year survival rate is only 7%[6]. Turaga et al[13] reported a median survival time of 24 months for patients with appendiceal. Signet ring cell carcinoma. The patient received adjuvant chemotherapy after surgery and has been followed for two years. Regular monitoring with tumor markers and imaging has revealed no evidence of recurrence, and follow-up is ongoing[14-17].

In this case, the appendix was enlarged and exhibited concentric wall thickening, consistent with the findings reported by Cho et al[14]. Both CT and MRI demonstrated gradual progressive enhancement following contrast administration, resembling the enhancement pattern described by Wang et al[16]. The uterus and cervix, affected by tumor implantation, showed diffuse thickening with an indistinct junctional zone. The uterine serosal layer remained intact, and the uterine lesions exhibited gradual progressive enhancement similar to the primary appendiceal lesion.

Based on this case and a review of the literature, several insights can be summarized: (1) Following implantation of Signet ring cell carcinoma to the uterus, diffuse thickening of the uterine myometrium may occur, often involving the cervix; (2) MRI characteristics of both primary and implantation lesions typically include iso-intensity on T1WI, iso- to hyperintensity on T2WI, slightly increased signal on DWI, with both CT and MRI showing gradual progressive enhancement after contrast administration; and (3) A small amount of ascitic fluid may be present in the pelvic cavity.

Preoperative accurate diagnosis is critical, as it may necessitate modifications in the surgical approach and the extent of resection[18]. Patients with appendiceal malignancy often present with symptoms and signs that mimic acute appendicitis[7]. In this case, the appendix appeared enlarged with concentric wall thickening, without signs of exudation, and was clearly demarcated from surrounding tissues; therefore, acute appendicitis was not considered. However, both preoperative CT and MRI failed to establish an accurate diagnosis. The uterine lesion was preoperatively misdiagnosed by MRI and clinically as adenomyosis.

Retrospective analysis revealed that the Signet ring cell carcinoma had metastasized to the uterus, and several features distinguished it from uterine adenomyosis: (1) Adenomyosis commonly presents with dysmenorrhea[19], whereas this patient had no history of abdominal pain; (2) Adenomyosis typically involves the uterine myometrium and rarely affects the cervix, while in this case, both the uterus and cervix were involved; and (3) Typical MRI findings of adenomyosis include high signal intensity in the myometrium on T2WI and focal high signal on T1WI in cases of hemorrhage[20]. In contrast, this case demonstrated significant myometrial thickening with an indistinct junctional zone and lacked focal high signal on both T1WI and T2WI.

The differential diagnosis of appendiceal signet ring cell carcinoma should include endometrial carcinoma, cervical cancer, and Krukenberg tumors. Endometrial carcinoma is one of the most common gynecologic malignancies[21], with lesions typically confined to the endometrial cavity. While it may invade the myometrium, the extent is usually limited. On DWI, endometrial carcinoma generally exhibits high signal intensity. In contrast, uterine implantation from SRCC tend to involve the uterus diffusely, with DWI signals that are less intense than those of endometrial carcinoma. Cervical cancer is the second most common malignancy in women[22], often originating in the cervix and potentially spreading upward to the uterus or downward to the vagina. It usually presents as a high-intensity signal on DWI. However, signet ring cell carcinoma implantation to the uterus show diffuse thickening of both the uterus and cervix, with lower DWI signal intensity than cervical cancer. Krukenberg tumors—metastatic ovarian tumors commonly originating from the gastrointestinal tract—affect both ovaries in approximately 80% of cases[23]. MRI findings typically include well-defined margins, predominantly solid components, and marked heterogeneous enhancement following contrast administration. Ascites is frequently present[24]. In comparison, signet ring cell carcinoma implantation to the uterus demonstrate lower degrees of enhancement and ascites is rarely observed.

CONCLUSION

Appendiceal Signet ring cell carcinoma is relatively rare, and preoperative diagnosis remains challenging. However, when imaging reveals thickening of the appendiceal wall alongside marked thickening of the uterine myometrium, with lesions demonstrating progressive enhancement after contrast administration, implantation appendiceal signet ring cell carcinoma involving the uterus should be considered.