A case of pulmonary tumor embolism diagnosed with respiratory distress immediately after FDG-PET/CT scan

Acute distress immediately following an ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan is an exceedingly rare event. We report a case whose condition was suddenly deteriorated in the nuclear medicine laboratory, and whose diagnosis was confirmed by FDG-PET/CT. A 67-year-old woman with left renal cell carcinoma (RCC) suddenly complained of dyspnea and tachycardia just after undergoing FDG-PET/CT. PET/CT images showed increased FDG uptakes in the left renal vein, inferior vena cava, right atrium, and bilateral hila. She was diagnosed with a massive tumor embolism from the inferior vena cava to both pulmonary arteries, and urgently underwent tumor embolectomy. FDG-PET/CT was helpful for diagnosing the tumor embolism and differentiating it from bland thromboembolism in this patient with RCC.

Primary perivascular epithelioid cell tumor (PEComa) in bone: A review of the literature and a case arising in the humerus with multiple metastases

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First case PEComa primary arising in humerus was described.

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Histology is the basic to determine malignancy of PEComa.

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TFE3 gene investigation is the key of therapy selection.

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mTOR inhibitor is believed to be effective for patients without TFE3 rearrangement.

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More study is needed to understand the role of molecular test and imaging in PEComa.

Introduction

Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal tumors that rarely arise as a primary bone tumor.

Material and methods

We report a case of primary malignant bone PEComa. A literature review via PubMed, Embase and Web of Science databases with the keyword “PEComa” and “bone” was performed.

Results

We reported a 33-year-old female with primary malignant bone PEComa in right distal humerus. The patient received an inhibitor of the mammalian target of rapamycin (mTOR) protein based on negative molecular investigation result of transcription factor E3 (TFE3) rearrangement, and additional therapies including palliative radiotherapy, anti-angiogenics and immunotherapy when the disease progression was detected. The patient was alive with the disease twenty-three months postoperatively. A total of nineteen related literature cases were retrieved and reviewed. Taking current case into account, ten males and ten females with median age of 24 years (range, 3–93 years) were identified, who were most frequently affected in tibia. The median follow-up duration of 24 months (range, 3–96 months). One patient died due to this disease, and six patients showed metastases. Three patients experienced recurrence, and two of them experienced twice and three times, respectively.

Conclusion

To our knowledge, this is the first case of primary malignant bone PEComa arising in humerus. Clinicopathological and radiological correlation is mandatory to the correct diagnosis and to determine its malignancy. More studies are required to understand the role of molecular test and imaging in selecting suitable treatment and mechanisms of treatment resistance.

Pneumothorax caused by cystic and nodular lung metastases from a malignant uterine perivascular epithelioid cell tumor (PEComa)

Perivascular epithelioid cell tumors (PEComas) are mesenchymal neoplasms with immunoreactivity for both melanocytic and smooth muscle markers. PEComas occur at multiple sites, and malignant PEComas can undergo metastasis, recurrence and aggressive clinical courses. Although the lung is a common metastatic site of PEComas, they usually appear as multiple nodules but rarely become cystic or cavitary. Here, we describe a female patient whose lungs manifested multiple cystic, cavity-like and nodular metastases 3 years after the resection of uterine tumors tentatively diagnosed as epithelioid smooth muscle tumors with uncertain malignant potential. This patient's subsequent pneumothorax necessitated video-assisted thoracoscopic surgery, and examination of her resected lung specimens eventually led to correcting the diagnosis, i.e., to a PEComa harboring tuberous sclerosis complex 1 (TSC1) loss-of-heterozygosity that originated in the uterus and then metastasized to the lungs. The administration of a gonadotropin-releasing hormone analogue later stabilized her clinical course. To the best of our knowledge, the present case is the first in the literature that associates PEComas with a TSC1 abnormality. Additionally, the pulmonary manifestations, including imaging appearance and pneumothorax, somewhat resembled those of lymphangioleiomyomatosis, a representative disease belonging to the PEComa family. Although PEComas are rare, clinicians, radiologists and pathologists should become aware of this disease entity, especially in the combined clinical setting of multiple cystic, cavity-like, nodular lesions on computed tomography of the chest and a past history of the tumor in the female reproductive system.