Anisakiasis mimics cancer recurrence: two cases of extragastrointestinal anisakiasis suspected to be recurrence of gynecological cancer on PET-CT and molecular biological investigation

Abstract

BackgroundWe report two cases of anisakiasis lesions that were initially suspected to be recurrence of gynecological cancer by positron emission tomography-computed tomography (PET-CT). Both cases were extragastrointestinal anisakiasis that is very rare.Case presentationThe first case was a patient with endometrial cancer. At 19 months after surgery, a new low density area of 2 cm in diameter in liver segment 4 was found on follow-up CT. In PET-CT, the lesion had abnormal 18fluoro-deoxyglucose (FDG) uptake with elevation in the delayed phase, with no other site showing FDG uptake. Partial liver resection was performed. A pathological examination revealed no evidence of malignancy, but showed necrotic granuloma with severe eosinophil infiltration and an irregular material with a lumen structure in the center. Parasitosis was suspected and consultation with the National Institute of Infectious Diseases (NIID) showed the larvae to be Anisakis simplex sensu stricto by genetic examination.The second case was a patient with low-grade endometrial stromal sarcoma (LG-ESS). At 8 months after surgery, swelling of the mediastinal lymph nodes was detected on CT and peripheral T-cell lymphoma was diagnosed by biopsy. A new peritoneal lesion with abnormal FDG uptake was detected on pre-treatment PET-CT and this lesion was increased in size on post-treatment PET-CT. Tumorectomy was performed based on suspected dissemination of LG-ESS recurrence. The findings in a pathological examination were similar to the first case and we again consulted the NIID. The larvae was identified as Anisakis pegreffi, which is a rare pathogen in humans.Having experienced these rare cases, we investigated the mechanisms of FDG uptake in parasitosis lesions by immunohistochemical staining using antibodies to glucose transporter type 1 (GLUT-1) and hexokinase type 2 (HK-2). While infiltrated eosinophils were negative, macrophages demonstrated positive for both antibodies. Therefore, mechanisms behind FDG uptake may involve macrophages, which is common among various granulomas. This is the first report to investigate parasitosis in such a way.ConclusionThese cases suggest that anisakiasis is a potential differential diagnosis for a lesion with FDG uptake in PET-CT, and that it is difficult to distinguish this disease from a recurrent tumor using PET-CT alone.

Morphological and Molecular Characteristics of Anisakis typica Larvae in Two Species of Threadfin Bream, Nemipterus hexodon and N. japonicus, from the Gulf of Thailand

“…There have been many reports of cases of anisakiasis in Asia and Europe, especially in Japan, which has popularised cuisine made with raw or undercooked seafood such as sushi and sashimi [7][8][9][10]. In Thailand, which also has a high level of consumption of raw seafood, eating raw fish or squid with dipping sauce or cooked into spicy seafood salad is common.…”

Unexpected hosts: imaging parasitic diseases

“…Specific and advanced imaging techniques for instance those of magnetic resonance (e.g. perfusion and diffusion-weighted images, spectroscopy, cholangiography sequences, hepatobiliary contrast agents), or combined radiology-nuclear medicine tests, such as positron emission tomography-computed tomography (PET-CT), can be helpful in solving the differential diagnosis, especially when parasitic disease mimics malignant neoplasms [2–8]. …”

Hepatic Anisakiasis in Japan

“…of the digestive tract [1], and gastrointestinal anisakiasis is the most commonly occurring condition (occurrence rate, >99%), particularly gastric anisakiasis [1,5]. Anisakiasis commonly presents with acute abdominal symptoms caused by an allergic reaction in the gastric mucosa [2]. Although the incidence of extra-gastrointestinal anisakiasis, such as the formation of granuloma due to Anisakis infection in the lungs, omentum, peritoneum, liver, pancreas, and ovary, is uncommon [6], its incidence rate among anisakiasis cases has been reported to be 0.2%-0.47% in Japan [2,5,7].…”

“…Anisakiasis commonly presents with acute abdominal symptoms caused by an allergic reaction in the gastric mucosa [2]. Although the incidence of extra-gastrointestinal anisakiasis, such as the formation of granuloma due to Anisakis infection in the lungs, omentum, peritoneum, liver, pancreas, and ovary, is uncommon [6], its incidence rate among anisakiasis cases has been reported to be 0.2%-0.47% in Japan [2,5,7]. Generally, medical history regarding the consumption of raw or undercooked seafood is not very important for the diagnosis of extra-gastrointestinal anisakiasis [7]; however, it may be useful for the diagnosis of gastrointestinal anisakiasis, which mainly occurs within half a day in case of gastric anisakiasis and within 1 week in case of intestinal anisakiasis following the consumption of raw or undercooked seafood [1].…”

“…A literature search was performed using the following keywords: (1) hepatic anisakiasis; (2) extra-gastrointestinal anisakiasis; and (3) liver tumor and anisakiasis. All the 13 cases (eight case reports [2,3,[5][6][7][8][9][10] and five proceedings [11][12][13][14][15]) have been reported in Japan, of which two cases have been reported in English [2,6] and remaining 11 in Japanese [3,5,[7][8][9][10][11][12][13][14][15].…”