Large Paraesophageal Schwannoma With Intense Prostate-Specific Membrane Antigen Expression on 68Ga-PSMA-PET/CT Mimicking Lymph Node Metastasis in a Patient With Prostate Cancer

PET/CT and contrast-enhanced CT imaging findings in benign solitary schwannomas

OBJECTIVES

Imaging features of positron emission tomography (PET)/computed tomography (CT) and contrast-enhanced CT and pathological changes in benign solitary schwannoma were retrospectively analyzed, and the factors associated with high uptake of fluorodeoxyglucose (FDG) were examined.

METHODS

The PET/CT, contrast-enhanced CT, and pathological results of 58 cases of benign solitary schwannomas confirmed by surgery or biopsy were retrospectively analyzed. The association of each variable with the maximum standardized uptake value (SUVmax) was evaluated.

RESULTS

The SUVmax of the 58 benign schwannoma cases was 4.1 ± 2.1 (1.5-11.1). When the locations of schwannomas were divided into gastrointestinal system/heart/abdominal and pelvic cavities/thoracic wall (type-1 locations) and other sites (type-2 locations), the schwannoma location was significantly correlated with the SUVmax (r = 0.538, p =  0.000). The SUVmax values were 5.8 ± 2.4 and 3.3 ± 1.5, respectively (p =  0.000). Peritumoral lymphoid cuffs were observed in 7 cases, 4 of which were tumors of gastrointestinal origin, accounting for 80 % of the gastrointestinal schwannomas (4/5). The presence of peritumoral lymphoid cuffs was significantly correlated with the SUVmax (r = 0.456, p =  0.000). The location of the schwannoma was significantly correlated with the presence of peritumoral lymphoid cuffs (r = 0.640, p =  0.000). We found that a peritumoral lymphoid cuff is strongly correlated with the presence of regional lymphadenopathy. Among the 7 cases showing peritumoral lymphoid cuffs, 5 cases had the presence of peritumoral enlarged lymph nodes. The degree of enhancement was significantly correlated with the SUVmax (r = 0.556, p =  0.000).

CONCLUSIONS

Benign schwannomas originating from the gastrointestinal system/heart/abdominal location and showing the presence of peritumoral lymphoid cuffs or moderate and significant enhancement on contrast-enhanced CT were significantly associated with high FDG uptake. An accurate understanding of the factors associated with high FDG uptake can help reduce the misdiagnosis rate.

Clinicopathological features of esophageal schwannomas in mainland China: systematic review of the literature

OBJECTIVE

Esophageal schwannoma (ES) are rare and mostly benign neurogenic tumors. The clinical misdiagnosis rate of it is high. In this study, the clinicopathologic features of ES in mainland China were studied to better understand the disease and improve the diagnosis and treatment rate.

METHODS

A systematic review was conducted in accordance with PRISMA guidelines. The keywords "esophageal schwannoma", "esophageal neurinoma" and "esophageal neurilemoma" were searched for databases such as Pubmed, EMbase, Wanfang Database and Chinese National Knowledge Infrastructure. The search time frame for database was until July 2019. Combined with our patient, the clinicopathological data and the diagnosis and treatment of ES were summarized.

RESULTS

ES occurs in the upper part of the mediastinum and in the thoracic esophagus in most patients in the neck, upper and middle segments. CT and PET/CT examinations can be used for diagnosis, but the differentiation value of both benign and malignant ES is similar. The histopathological findings of forceps biopsy specimens are often difficult to diagnose, and deep tissue biopsies may increase pathological accuracy. EUS-FNA is also recommended for ES diagnosis, but it may also be misdiagnosed. Pathological features include a fusiform arrangement in a palisade-like structure or a tumor cell arranged in a network to form a loose structure. ES characteristic immunohistochemistry results showed that S-100 protein has strong immunological activity.

CONCLUSION

The definitive diagnosis requires immunohistochemistry, especially immunological reaction with S-100 protein. The appropriate treatment plan should be selected according to the diameter of the lesion. The overall prognosis of ES is good, but attention should be paid to follow-up.

Pulmonary Vein Varix Mimicking Prostate Cancer Metastasis on 68Ga-Prostate Specific Membrane Antigen-11 PET/CT

The use of PET/CT with prostate-specific membrane antigen radioligands for staging prostate cancer patients presenting a biochemical recurrence is increasing. As a consequence, the number of reports of diagnostic pitfall of this imaging modality is also increasing. A 75-year-old man referred for a second episode of biochemical recurrence of prostate cancer presented an isolated intense prostate-specific membrane antigen-11 uptake from a right lung abnormality. This abnormality was suggestive of pulmonary vein varix on contrast-enhanced lung CT. The uptake remained stable 1 month after starting androgen deprivation therapy, which confirmed the diagnostic of pulmonary vein varix.