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.

The need for bone biopsies in the diagnosis of new bone lesions in patients with a known primary malignancy: A comparative review of 117 biopsy cases

Objective

This study used a clinical dataset to investigate the proportion of the newly found bone lesions in malignant patients diagnosed by biopsy as being benign, malignant but unrelated to the primary malignancy, or bone metastases of the primary malignancy. The clinical factors that might affect the correlation between bone lesions and the primary malignancy were also analyzed. It is expected to obtain some information contributing to the clinical decision-making regarding the need for biopsy of these lesions from the research results.

Methods

Data from patients with a single known malignant tumor who had undergone biopsy of newly found bone lesions at our research institution between January 2012 and December 2017 were reviewed. Based on the pathology results, included cases were divided into a bone-metastasis-of-primary-tumor group (Group 1) and a non-bone-metastasis-of-primary-tumor group (Group 2). The sex, age, diagnostic interval time between the primary malignancy and bone lesions, clinical symptoms, number of involved bones, sites of bone biopsy, and ¹⁸F-FDG PET/CT results were compared between groups.

Results

A total of 117 patients (92 in Group 1 and 25 in Group 2) were included in the study. There was no significant difference in the sex, age or diagnostic interval time between patient groups. Of all the cases, 17.9% (21/117) were identified to be benign lesions such as fibrous dysplasia (n = 2), bone tuberculosis (n = 1), simple bone cyst (n = 1), aneurysmal bone cyst (n = 1), or solitary fibrous tumor (n = 1). Meanwhile, 3.4% (4/117) were new malignancies including chondrosarcoma (n = 1), plasmacytoma (n = 1) and bone metastases unrelated to the primary malignancy (n = 2). Bone metastases pertinent to the primary tumor accounted for 78.6% (92/117) of cases. Liver (n = 18), kidney (n = 14), breast (n = 13) and lung (n = 12) were the most common cancers among cases. Cases with clinical symptoms exhibited a higher likelihood of their bone lesions being diagnosed as bone metastases of their primary malignancy than those without clinical symptoms (81.3% (87/107) vs. 50.0% (5/10)) (P = 0.021). Neither the number of bone lesions nor the biopsy sites appeared to influence whether the bone lesions were metastases of the primary malignancy or not. In PET/CT examination, the mean maximum standardized uptake values of the two groups were similar.

Conclusions

This study indicated that more than 1/5 of newly identified bone lesions in patients with a single known malignancy were not clinically associated with their primary tumors. Furthermore, 3.4% of these were newly discovered malignant bone tumors. The presence of clinical symptoms may be a significant factor affecting whether a new bone lesion is clinically linked to a patient's primary malignancy. Based on the experience from these patients, as for the newly found bone lesions, it is worthy to perform an active biopsy on those asymptomatic ones to avoid misdiagnosis and less biopsy on symptomatic ones for the sake of less cost and risks.

Burkitt lymphoma involving jejunum in children

A 5-year-old boy presented with 3-month bloody stool from unknown origin and progressive anemia. In this case report, we review the incidence, diagnosis, pathology, treatment and prognosis of Burkitt Lymphoma.