Rationale:Langerhans cell histiocytosis (LCH) involves mainly the skin and bone and rarely the thyroid. Meanwhile, papillary thyroid carcinoma (PTC) is the most common subtype of thyroid cancer. Both LCH and PTC could make the thyroid enlarged and hypermetabolic. The coincidence of these 2 events in a patient is rare, and this paper aimed to report such case.Patient concerns:A 40-year-old man presented with polyuria and polydipsia for 5 years. The symptoms had been relieved well by drug therapy for >4 years, until the drugs could not control the symptoms anymore and an extensively enlarged thyroid gland was noticed.Diagnoses:Thyroid ultrasound showed a nodule with microcalcification in the upper right lobe, positron emission tomography/computer tomography scan demonstrated thyroid hypermetabolism, and fine needle aspiration (FNA) revealed PTC. Right lobectomy of the thyroid and cervical lymph node biopsy verified the diagnosis “LCH of the thyroid complicated by PTC.”Interventions:The ultrasound-guided FNA biopsy was performed prior to right lobectomy of the thyroid and cervical lymph node biopsy. Postoperative histopathological examination confirmed the diagnosis, after which the patient received adjuvant chemotherapy.Outcomes:After 5 cycles of adjuvant chemotherapy, the patient had been followed up for 2 years. LCH was controlled satisfactorily and there was no significant sign of recurrence or metastasis of PTC.Lessons:LCH of the thyroid complicated by PTC is rare. Thyroid involvement should always be considered in the differential diagnosis of LCH patients. Surgery for PTC followed by chemotherapy for LCH may be the suitable treatment.

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A 23-year-old woman with recurrent uterine endometrial stromal sarcoma underwent FDG PET/CT, which showed pelvic recurrence and multiple pulmonary metastases. In addition, increased activity in a vertical soft tissue mass along the left ureter was noted, which appears similar to retroperitoneal fibrosis on PET/CT images. However, pathological examination demonstrated that the elevated FDG activity in this mass was a result of tumor thrombus from endometrial stromal sarcoma in the left ovarian arteries and veins.

A 69-year-old woman complaining of abdominal bloating underwent ultrasonography, which revealed a small lesion in the left lobe of the liver. The lesion had elevated activity of both 18F-FDG and 11C-acetate on PET/CT scan and was suspected of being malignant. Postresection pathological examination demonstrated that this lesion was a focal intrahepatic lymphoid hyperplasia.