Expression of Programmed Death Ligand 2 in Patients with Thymoma and Thymomatous Myasthenia Gravis

Purpose: The purpose of this study was to examine the expression of PD-L2 in thymoma and thymomatous myasthenia gravis (MG). Methods: The records of 70 patients with thymoma who underwent surgical resection between January 2017 and December 2018 were retrospectively reviewed. Thymoma PD-L2 expression was evaluated by immunohistochemistry (IHC) staining. Associations between PD-L2 expression and clinicopathological features were examined. Results: PD-L2 expression was positive in 41 patients (58.6%) and negative in 29 patients (41.4%). Of the patients, 33 had thymomatous MG. Patients with MG were more likely to be ≤ 50 years of age (69.70% vs. 35.14%), have higher WHO type (84.85% vs. 64.86%), smaller tumor size (4.09 ± 2.33 vs. 6.47 ± 2.42 cm), have positive PD-L2 expression (78.79% vs. 40.54%), and have higher PD-L2 expression intensity, ratio, and score (all, P < 0.05). Positive PD-L2 expression was associated with higher WHO type, higher Masaoka-Koga stage, smaller tumor size, ectopic thymus, and MG (all, P < 0.05). Factors significantly associated with MG were age > 50 years (OR = 0.09, 95% CI: 0.02 to 0.39), tumor size > 5 cm (OR = 0.22, 95% CI: 0.06 to 0.82), and positive PD-L2 expression (OR = 9.25, 95% CI: 1.93 to 44.30) (all, P < 0.05; Table 3).Conclusion: Thymoma PD-L2 expression is significantly associated with thymomatous MG and WHO histological type B2 and B3.

Subglottic ectopic thymus mimicking airway haemangioma

Subglottic haemangioma presents as progressive obstruction in the neonatal and infantile airway, with a soft lesion seen during endoscopy. Diagnosis is based on macroscopic findings, biopsy is not usually performed and propranolol is first-line treatment. In contrast, ectopic thymus is a rare differential diagnosis for subglottic mass made by histopathological examination after excision or autopsy. In this article, we present a case of an infant with a subglottic lesion with endoscopic features consistent with haemangioma. After initial clinical response to propranolol, the patient represented with progressive stridor no longer responding to therapy. Open excision of the lesion was performed, and histopathology revealed ectopic thymus tissue. In this case, ectopic thymus tissue mimicked the presentation of subglottic haemangioma, and confirmation bias persisted due to an apparent initial clinical response to treatment with propranolol. In cases of subglottic mass refractory to medical treatment, excision of the lesion should be considered.

Intrathyroidal Ectopic Thymus and Sonoelastographic Findings

Background: Intrathyroidal ectopic thymus (IET) can be misdiagnosed as thyroid nodules. Purpose: To evaluate the sonoelastographic findings of IET in pediatric population. Methods: Twelve children who had been examined with ultrasound (US) and strain elastography between December 2012 and December 2019 were included in this retrospective study. The patients’ demographics and ultrasonographic findings including the location, margin, shape, diameters, volume, structure, vascularity, and elastography values of the lesions were evaluated. Results: Twelve lesions were detected in 12 asymptomatic patients (3 females and 9 males) with a mean age of 4.67 ± 2.27 years. The most common location of the IET was in posterior part and middle third of thyroid, and the most common appearance on US was a well-defined, ovoid-shaped, and predominantly hypoechoic solid lesion with punctate/linear branching hyperechogenities. The lesions were mostly hypovascular on Doppler US. The mean strain ratio on elastography was found to be 1.10 ± 0.04. In the follow-up of 7 patients with available information, there was not any significant change in size or appearance of IET on US. Conclusion: IET should be considered in the differential diagnosis of the lesions within the thyroid. The first step to accurately diagnose an IET is to consider it in the differential diagnosis. In addition to US, strain elastography findings can be used to distinguish IETs from papillary thyroid cancers which can have similar US appearance, and help avoid unnecessary biopsies.

Interobserver Agreement and Plane-Dependent Intraobserver Variability of Shear Wave Sonoelastography in the Differential Diagnosis of Ectopic Thymus Tissue

Shear wave elastography (SWE) has been demonstrated to be a useful tool in the differential diagnosis of ectopic thymus tissues (ETs), providing quantitative values of the shear wave stiffness (SWS) of both ETs and adjacent thyroid tissue. However, no data are available on the potential influence of the imaging plane (transverse vs. longitudinal) on the obtained SWS and shear wave ratio (SWR) values in SWE of these tissues. Moreover, no reports on the interobserver repeatability of SWE were published in regard to ETs. The aim of this study has been to evaluate the potential influence of the examination plane—transverse vs. longitudinal—on the SWS and SWR results, as well as to determine whether SWE of ETs is subjected to interobserver variability. SWE was demonstrated to have high inter- and intraobserver agreement in the evaluation of ETs and adjacent thyroid tissue. Significant differences between SWS values, but not SWR values, obtained in the transverse and longitudinal planes were observed. This phenomenon is probably a result of anisotropy-related artifacts and does not reduce the reliability of the method. SWE operators should be aware of the presence of plane-dependent artifacts to properly interpret the obtained results.

Application of Shear Wave Sonoelastography in the Differential Diagnosis of Extra- and Intra-Thyroidal Ectopic Thymic Tissue

The ultrasound (US) pattern of intrathyroidal ectopic thymus (IET) can resemble papillary thyroid carcinoma (PTC) while the extrathyroidal ectopic thymus (EET) can mimic pathological lymph nodes. Recently, the usefulness of strain elastography (SE) was demonstrated in the differential diagnosis, however this method has several limitations. The aim of the current study was to assess the usefulness of shear wave elastography (SWE) in this field. The US, SE, and SWE were performed in 31 children with 53 ectopic thymuses (ETs) and quantitative values of SWE parameters were calculated, so as to generate potential normative values of ET elasticity and of the shear wave ratio (SWR). The mean SWRIET was 0.89 ± 0.21 and the mean shear wave stiffness (SWS) was 7.47 ± 1.93 kPa. The mean SWREET was 0.84 ± 0.15 and the mean SWSEET was 11.28 ± 2.58 kPa. The results have proven that the stiffness of ETs is lower or equal to the thyroid’s. SWE was demonstrated to be a useful diagnostic method for ET evaluation. Therefore, the application of SWE in ET diagnosis allows more accurate evaluation of ET-like lesions and, in many cases, allows one to avoid invasive procedures, simultaneously providing a precise monitoring method based on combined US and SWE evaluation.

Ectopic Cervical Thymus: A Common, yet Rarely Symptomatic Pediatric Neck Mass

Abstract:: Ectopic thymic tissue is an unusual finding that is generally asymptomatic. We present a case series of five pediatric patients with cervical ectopic thymuses. In two patients, the ectopic thymic tissue was symptomatic, and in three patients it was an incidental finding. We highlight the need to include this anomaly on the differential diagnosis for a pediatric neck mass. We also propose observation, rather than surgical excision, as the treatment of choice for asymptomatic cervical ectopic thymus.