PEM case of the week: vomiting in a well-appearing teenager
A 16-year-old boy is brought to the pediatric ED by his sister and father.
Chief complaint: vomiting
He has no medical or surgical history. He reports worsening intermittent episodes of upper abdominal pain, nausea, and non-bloody vomiting after eating. He tolerates oral fluids and very small amounts of solid food. When he is not eating, he has no pain, nausea, or vomiting.
The rest of the review of systems is unrevealing: no fever, cough, sore throat, chest pain, dyspnea, change in bowel habits, urinary symptoms, or testicular pain. There are no sick contacts or recent travel, and his vaccinations are up to date.
Exam
Awake, alert, and well appearing.
TMs and ear canals normal. No posterior oropharyngeal swelling, erythema, or exudate.
No palpable lymphadenopathy; moist mucous membranes.
Lungs clear; normal heart sounds.
Abdomen soft, non-tender in all quadrants, non-distended, with no CVA tenderness.
What do you do next?
Work-up
CBC, CMP, and lipase were ordered, along with an abdominal X-ray and a CT abdomen/pelvis with oral and IV contrast. The CBC, CMP, and lipase were normal. Then the CT images came back.
CT impression
A 12.5 cm splenic lesion that may represent an echinococcal cyst, with mass effect compressing the stomach. MRI with and without contrast was recommended.
Hospital course
Surgery was consulted, and the patient was admitted to pediatrics for further work-up, with infectious disease and gastroenterology consultations and MRI.
Further history revealed a family trip to Mexico the previous year. ID and surgery recommended holding treatment until the diagnosis was confirmed.
MRI impression: a 12.5 × 12.5 × 14.9 cm simple cyst in the spleen, predominantly anterior, with no complexity. Two small splenules were noted.
Final diagnosis: a large simple splenic cyst, not an echinococcal cyst.
Plan: elective, non-emergent splenectomy with outpatient pediatric surgery and ID follow-up. ID follow-up is needed for vaccination before splenectomy (for example, pneumococcal and meningococcal vaccines). GI planned to evaluate other causes of his symptoms, including H. pylori and stool studies.
Because he tolerated food and fluids in the hospital, the consultants felt an underlying viral illness may have triggered the presentation.
Why this case matters
Whether the cyst's mass effect or a GI virus caused his symptoms is almost beside the point. Had the cyst not been found, he would have been at very high risk of splenic injury from traumatic or spontaneous rupture, and the stakes would have been even higher if it had been a true echinococcal cyst.
Learning points
Consider physical obstruction in the differential for vomiting, including extrinsic compression.
The history is so important. Given his very well-appearing exam, a PO challenge with outpatient work-up would not have been unreasonable. Vomiting reliably triggered by eating was concerning enough to pursue imaging.
Echinococcosis: a brief review
A parasitic disease caused by Echinococcus granulosus and E. multilocularis.
Humans are infected by ingesting eggs in contaminated food, soil, or water, or through direct contact with hosts. Hosts include sheep, goats, swine, cattle, rodents, dogs, cats, foxes, and wolves.
It can be asymptomatic for years. The parasite penetrates the intestinal mucosa and spreads hematogenously to form cysts (hydatid cysts), most often in the liver, but also in the lungs or spleen.
Treatment: typically started with albendazole 400 mg PO twice daily for 1–6 months (pediatric dosing 10–15 mg/kg/day, max 800 mg/day). Praziquantel may be used when there is concern the parasite could spread from the cyst. Chemotherapy is also used as treatment for alveolar-based cysts.
From the ED, the best path is either admission for ID consultation or discharge with urgent ID follow-up.
For more on the risks and potential complications, see the case report by Bruijn et al. (below).
References
Echinococcosis. WikEM. Published October 2, 2019. Accessed April 13, 2026.
CDC. Clinical treatment of echinococcosis. May 13, 2024. Accessed April 13, 2026.
Bruijn SD, Weerdt AD, Broeckx G, et al. Multimodal treatment of a spontaneously ruptured echinococcus cyst of the spleen and its complications. Case Rep Gastrointest Med. 2025;2025(1):6657981. doi:10.1155/crgm/6657981
