Correct answer is: Colonic Crohn’s disease

Image findings

B-mode ultrasound revealed a thickened intestinal wall up to 4-5 mm with luminal narrowing while the stratified appearance of the bowel was lost. CEUS depicts enhancement of all layers in both the arterial as well as the venous phase of contrast-enhancement. Also, Color Doppler showed increased vascularization throughout the affected thickened segment. Furthermore, colonoscopy and CT colonography were performed, revealing the stenosis of the descending colon of about 13 cm long. The virtual colonoscopy also revealed a retroperitoneal fistula located at the level of the descending colon.

Discussion

Patients with Crohn’s disease frequently develop small bowel stricture, while only 15-25% of the patients develop colonic strictures alone (1). It is also known that within 10 years, around 15% of the patients develop a fibrostenotic disease phenotype (2). Usually, patients with stenotic Crohn’s disease may present obstructive symptoms, weight loss, chronic diarrhea or constipation whilst only a small percentage are asymptomatic (3).

Bowel strictures may contain different degrees of inflammation and fibrosis, with a large proportion of patients presenting an overlap between the 2 processes (4). The type of stricture is mostly important for the therapeutic management: inflammatory strictures could benefit from medical treatment, while fibrotic strictures necessitate endoscopic or surgical treatment. In this case, the fact that the colon is still well vascularized would imply that the patient has an inflammatory stricture and might benefit from anti-inflammatory treatment (5). Moreover, ahead of any surgical intervention, this patient was considered eligible to receive a monoclonal antibody drug (vedolizumab).

Regarding the imaging diagnosis, the ultrasound features cannot determine the final etiology of the stenosis. Wall thickening may be caused by several diseases, but as the patient has a history of Crohn’s disease, this is most likely the cause.

Conflicts of Interest

The authors declare no conflict of interest

References

1. Freeman HJ. Natural history and clinical behavior of Crohn’s disease extending beyond two decades. J ClinGastroenterol. 2003; 37: 216-219.
2. 1 Thia KT, Sandborn WJ, Harmsen WS, et al. Risk factors associated with progression to intestinal complications of Crohn’s disease in a population-based cohort. Gastroenterology. 2010; 139: 1147-1155.
3. Bettenworth D, Bokemeyer A, Baker M, et al. Assessment of Crohn’s disease-associated small bowel strictures and fibrosis on cross-sectional imaging: a systematic review. Gut. 2019; 68: 1115-1126.
4. Maconi G, Nylund K, Ripolles T, Calabrese E, Dirks K, Dietrich CF, Hollerweger A, Sporea I, Saftoiu A, Maaser C, Hausken T, Higginson AP, Nürnberg D, Pallotta N, Romanini L, Serra C, Gilja OH.EFSUMB Recommendations and Clinical Guidelines for Intestinal Ultrasound (GIUS) in Inflammatory Bowel Diseases.Ultraschall Med. 2018;39:304-317.
5. Ripollés T, Rausell N, Paredes JM, Grau E, Martínez MJ, Vizuete J.Effectiveness of contrast-enhanced ultrasound for characterisation of intestinal inflammation in Crohn’s disease: a comparison with surgical histopathology analysis.J Crohns Colitis. 2013;7:120-8.

Correct answer to Q1 is: Abnormal lymph nodes either due to abscess or malignancy.

Due to the inconclusive ultrasound examination the patient was referred to a CT of the abdomen as well as further blood samples at the department of infectious diseases. The CT was inconclusive too, and a fine needle aspiration of the lymph nodes (FNA) was suggested.

Correct answer to Q2 is: Tularemia.

Discussion:

Tularemia is a zoonosis caused by Francisella tularensis, a small aerobe gram-negative rod. Tularemia is very rare in northern Europe, with under 10 cases per year in Denmark. The most common disease vectors are rabbits and wild game, but ticks and mosquitoes can also carry and spread the infection. Typical symptoms include fever, muscle soreness, fatigue and lymphadenopathy. Diagnosis is usually confirmed using PCR or microbial culturing of samples. Oral antibiotics are effective, and complications are rare with adequate treatment. [1]

In the present case, ultrasound revealed an ovoid lymph node of moderate size, with no lobulation and no clear effacement of the hilum – typical traits of benign lymphadenitis [2]. However, the node had areas of considerable hypoechogenicity (see image 4), which is typically seen in areas of abscessing infection, or of necrosis in metastatic lymph nodes, especially in malignant melanoma. A lymph node with metastasis of malignant melanoma is typically hypoechoic and round, and the hilum may be effaced. The shape may also be irregular or lobulated. [3] When ultrasound reveals a lymph node exhibiting one or more of these traits, biopsy should be considered in order to rule out malignancy.

In the current case, purulent exudate was sampled from the lesion and cytology was not performed, as PCR soon confirmed infection with Francisella tularensis. The patient was treated with oral antibiotics, and the symptoms quickly subsided with no further complications.

As an interesting sidenote, because of the potential of Francisella tularensis to cause pulmonary tularemia through infection using aerosols, the Center for Disease Control considers tularemia to be a potential biological weapon threat. [4]

Conflicts of interest

“The authors declare no conflict of interest.”

References

1. Tularæmi (harepest) Available online: https://www.ssi.dk/sygdomme-beredskab-og-forskning/sygdomsleksikon/t/tularaemi (accessed on Dec 13, 2020).
2. Vassallo, P.; Wernecke, K.; Roos, N.; Peters, P.E. Differentiation of benign from malignant superficial lymphadenopathy: The role of high-resolution US. Radiology 1992, 183, 215–220.
3. Patnana, M.; Bronstein, Y.; Szklaruk, J.; Bedi, D.G.; Hwu, W.J.; Gershenwald, J.E.; Prieto, V.G.; Ng, C.S. Multimethod imaging, staging, and spectrum of manifestations of metastatic melanoma. Clin. Radiol. 2011, 66, 224–236.
4. CDC Tularemia | Emergency Preparedness & Response Available online: https://emergency.cdc.gov/agent/tularemia/ (accessed on Dec 13, 2020).