Recognizing Tumor Origin for Lymphoid Tumor of Unknown Primary via Total-Body PET/CT Scan-Case Report.

Weizhao Lu,Xue Xie,Min Li,Jianfeng Qiu,Yanhua Duan,Zhaoping Cheng,Kun Li,Chao Ma,Sijin Liu

doi:10.3389/fonc.2022.766490

Abstract

Localizing the site of tumor origin for patients with lymphoid tumor is fairly difficult before the definitive detection of the primary tumor, which causes redundant imaging examinations and medical costs. To circumvent this obstacle, the emergence of the world’s first total-body positron emission tomography/computed tomography (PET/CT) provides a transformative platform for simultaneously static and dynamic human molecular imaging. Here, we reported a case of lymph node metastasis from an unknown primary tumor, and the primary tumor was detected with the aid of the total-body PET/CT scanner. This patient with right neck mass was subjected to static and dynamic PET scan, as the static PET imaging found irregular thickening of the upper rectal wall and the dynamic PET imaging recognized the associations between the lymph metastasis and the rectal tumor lesions. The diagnosis by the total-body PET/CT was confirmed by pathological examination.

Highlights

Metastases is the leading cause of cancer mortality, yet few effective therapeutics are available to combat metastatic lesions [1], as existing therapeutics are predominantly specific to the primary tumor [2]
We report an unusual case with the aid of the total-body positron emission tomography/computed tomography (PET/computed tomography (CT)) to look for the unknown primary tumor
We reported the diagnosis of a patient with lymph node metastasis from an unknown primary tumor using the state-of-theart total-body positron emission tomography (PET)/CT examination

Summary

INTRODUCTION

Metastases is the leading cause of cancer mortality, yet few effective therapeutics are available to combat metastatic lesions [1], as existing therapeutics are predominantly specific to the primary tumor [2]. The immunohistochemistry results manifested positive staining for TTF-1 and CK7 (Figures 1B, C) and weak positive for AACT and AAT, and negative staining for CK20, CDX2, Villin, PSA, Napsin A, CD117, S-100, Tg, p63, and Ck5/6 in the right neck lesion These results together hinted a great probability of metastatic adenocarcinoma for the lymph lesion. The static total-body PET identified a marked increase in 18F-FDG uptake within the right neck mass with swollen lymph nodes (SUVmax = 21.0) (Region A in Figure 2), consistent with metastatic tumor manifestations [12]. As shown by the Pearson’s correlation coefficient and cosine similarity index (Figures 3B, C), among the four regions with abnormal 18F-FDG uptake, Region B displayed the closest relationship toward Region A, suggesting a great similarity between Regions A and B In this premise, it would be speculated that the rectal tumor was the primary tumor responsible for the right neck lymph node metastasis. The right neck mass was diagnosed with lymph node metastasis from an adenocarcinoma

DISCUSSION

CONCLUSION

ETHICS STATEMENT