Diagnosis of intrathyroidal ectopic thymus in thyroid fine needle aspiration samples

Detecting ectopic thymus in thymoma-associated myasthenia gravis through flow cytometry analysis of CD3mediumTCRvβmediumCD4+CD8+ T cells and its clinical significance

Background

Traditional histological methods for identifying ectopic thymus (ET) have significant limitations including high risk of false negatives. This study aims to evaluate the effectiveness of flow cytometry in detecting ETs in patients undergoing total thymectomy.

Methods

We analyzed 864 samples from 103 patients using flow cytometry and hematoxylin and eosin (H&E) staining. ETs were identified by the presence of CD3mediumTCRvβmediumCD4+CD8+ T cells in flow cytometry or Hassall's corpuscles in H&E staining.

Results

In the discovery set, flow cytometry detected ETs in 69.2% of samples, compared to 23.6% by histological methods. The validation set showed a higher incidence of ETs in myasthenia gravis (MG) patients than in non-MG patients (73.5% vs. 58.0%, P < 0.0001) and in those with thymic epithelial tumors versus normal thymus (68.1% vs. 58.1%, P = 0.0088). MG patients exhibited a higher prevalence of active ETs, characterized by a high proportion of CD4+CD8+ T cells, indicating robust thymopoiesis, compared to those without MG (P = 0.0001). Specific regions, such as the left cervical root, areas along the right and left phrenic nerves, and the left innominate vein, showed significantly higher activity (P < 0.05). Additionally, ETs were more frequently found in the cervical region than in the mediastinum (75.0% vs. 60.8%, P = 0.0012), and in patients aged 40 years or younger compared to those older than 40 years (73.0% vs. 60.6%, P = 0.0027).

Conclusions

Flow cytometry is a viable alternative for ET detection, providing a novel distribution map that enhances surgical decision-making in MG treatment.

Ectopic thyroid tissue in the airway: a case report

BACKGROUND

Ectopic thyroid tissue (ETT) is a rare congenital anomaly caused by the abnormal embryonic migration of thyroid tissue, leading to its presence outside its usual pretracheal location. This condition can lead to diagnostic challenges, especially when located within the airway, as it mimics other respiratory disorders such as asthma.

CASE PRESENTATION

We report the case of a 69-year-old man with endotracheal ETT presenting with severe dyspnea, and the lesion was initially suspected to be malignant. The diagnosis of ETT was confirmed through bronchoscopy and histopathological examination. The patient underwent successful endoscopic interventional therapy, resulting in significant symptom improvement and complete resolution of the airway lesion.

CONCLUSION

Although rare, ETT should be considered in the differential diagnosis of unexplained respiratory symptoms to prevent misdiagnosis and permit effective, minimally invasive treatment options such as endoscopic resection, which can significantly improve patient outcomes.

Insights into Thyroid and Salivary Gland Cytopathology: Highlights from a 45th European Congress of Cytology Slide Seminar

INTRODUCTION

Thyroid and salivary gland cytopathology frequently present diagnostic challenges due to complex presentations, overlapping features between benign and malignant conditions, particularly with gray-zone entities and rare pathologies. To address these issues, the 45th European Congress of Cytology (ECC) held a slide seminar focused on challenging cases. This article reviews key findings from the 6 cases discussed, emphasizing the importance of a comprehensive diagnostic approach. The objective of this article was to illustrate the diagnostic challenges of rare thyroid and salivary gland lesions through case presentations, showing the need for a comprehensive, multidisciplinary approach to accurately reach a final diagnosis and steer the patient's management.

CASE PRESENTATION

The seminar presented cases involving fine-needle aspiration cytology followed by histopathological correlation, molecular and cytogenetic analyses or immunohistochemistry (IHC) markers to elucidate cytomorphological features, differential diagnoses, and final diagnoses of rare cases in thyroid and salivary gland cytopathology. Challenging thyroid cytology cases included differentiating thyroid sarcoidosis from malignancy, identifying intrathyroidal ectopic thymus versus lymphoid neoplasms, and recognizing poorly differentiated thyroid carcinoma initially misinterpreted as a benign follicular neoplasm. Complex salivary gland cases addressed the distinction of basal cell adenocarcinoma from adenoid cystic carcinoma, metastatic SMARCB1-deficient carcinoma diagnosed via IHC and a parotid mass initially identified as a Warthin tumor.

CONCLUSION

These cases highlight the critical role of integrating cytological, clinical, and histopathological data to navigate the diagnostic complexities of thyroid and salivary gland lesions. A multidisciplinary approach and standardized algorithms are essential for improving diagnostic accuracy and patient outcomes.

[Intrathyroidal thymus can cause confusion in the diagnosis of a thyroid mass. A case report]

Intrathyroidal thymus tissue (ITTT) is a rare, benign condition; its diagnosis can prove challenging due to unfamiliarity with this entity. However, it has ultrasonographical and cytological characteristics which can suggest its presence and thus should be considered in the differential diagnosis of thyroid nodules. Presently, immunohistochemistry can be used with fine needle aspiration (FNA) cytology, thus decreasing the need for unnecessary surgery. We discuss the usefulness of immunohistochemistry in thyroid cytology, with reference to a case of a 10-year-old patient, who underwent partial thyroidectomy for a suspicious thyroid nodule which was eventually diagnosed as ITTT by the histopathology of the surgical specimen.

Flow Cytometric Evaluation of Surface and Cytoplasmic TRBC1 Expression in the Differential Diagnosis of Immature T-Cell Proliferations

OBJECTIVES

Flow cytometric detection of T-cell clonality is challenging, particularly in differential diagnosis of immature T-cell proliferations. Studies have shown utility of TRBC1, in conjunction with other T-cell markers, as reliable means to identify T-cell clonality by flow cytometry. One limitation of surface TRBC1 (sTRBC1) evaluation is it cannot be detected in surface CD3 (sCD3)-negative T cells, such as normal or abnormal immature T-cell precursors. Here, we assess surface and cytoplasmic TRBC1 expression patterns in the differential diagnosis of T-lymphoblastic leukemia/lymphoma (T-ALL) vs normal thymocyte expansions.

METHODS

Forty-three samples containing T-ALL, thymoma, normal thymus, and/or indolent T-lymphoblastic proliferation (i-TLBP), were evaluated.

RESULTS

All 24 cases with normal thymocytes or i-TLBPs revealed a characteristic and reproducible sCD3/sTRBC1 expression pattern indicative of polytypic T-cell maturation. In contrast, all 19 T-ALLs lacked this polytypic maturation pattern and were either completely negative for sCD3/sTRBC1 or showed a minor sCD3-positive subset with a monotypic TRBC1 expression pattern. Cytoplasmic TRBC1 evaluation in 9 T-ALLs demonstrated a monotypic intracellular TRBC1-positive (n = 4) or TRBC1-negative (n = 5) expression, indicative of clonality.

CONCLUSIONS

Our findings demonstrate flow cytometric evaluation of surface and cytoplasmic TRBC1 expression can aid detection of T-cell clonality and differential diagnosis of immature T-cell proliferations.

Echographic findings in ectopic intrathyroidal thymic tissue in children. A systematic review

Intrathyroidal ectopic thymic tissue (IETT) is an indulgent, unusual entity and is part of the differential diagnosis of thyroid nodules in the pediatric population. Because of the low prevalence of IETT, the diagnosis may be difficult. Awareness of this diagnosis is definitive to avoid surgical interventions. The aim of this study was to review the literature on the echographic characteristics of IETT. We conducted a search of Ovid, PubMed and the virtual health library. A total of 619 patients with a mean age of 6.2 years old were included. IETT was located in the lower portion of both of the thyroidal lobes in 556 children, the echographic shape was reported for 173 patients, with the fusiform shape as the most representative, the appearance of the IETTs was reported for 121 patients, the most common was the hypoechogenic pattern with multiple internal echogenic foci. The average lesion diameter was 5.53 mm, and Doppler findings reported a hipovascular pattern in 56% of the lesions. In conclusion, IETT is an infrequent entity; nonetheless, it must be considered in the differential diagnosis of neck nodules in children and should be study and follow with echography to avoid unnecessary surgery.

CD2 and CD7 are sensitive flow cytometry screening markers for T-lineage acute leukemia(s): a study of 465 acute leukemia cases

T-lymphoblastic leukemia/lymphoma (T-ALL/LBL) is a rare acute leukemia that expresses cytoplasmic CD3 (cCD3) and frequently lacks surface CD3. Given that routine flow cytometric testing for cCD3 may not be feasible and cCD3 interpretation may be difficult, we investigate if surface CD2 and/or CD7 expression on blasts can be used by flow cytometry to screen for T-lineage acute leukemia. We retrospectively reviewed flow cytometric data from 233 acute leukemias (36 T-ALL/LBL, 8 mixed-phenotype acute leukemia T/myeloid, 80 acute myeloid leukemia, 97 B-ALL/LBL, 8 mixed-phenotype acute leukemia B/myeloid, and 4 acute undifferentiated leukemia cases). Uniform expression (≥75% of blasts) of CD2 and/or CD7 was seen in all 44 cCD3-positive cases but in only 11% (20/189) of cCD3-negative acute leukemias, thus demonstrating 100% sensitivity and 89% specificity in the identification of cCD3-positive (T-lineage) acute leukemia. To avoid selection bias, we prospectively studied 232 consecutive acute leukemias for which cCD3, CD2, and CD7 were automatically performed in all cases. Similar to the retrospective study, uniform expression of CD2 and/or CD7 on blasts showed 100% sensitivity and 88% specificity in the screening for cCD3-positive (T-lineage) acute leukemia. Therefore, acute leukemias with uniform expression of CD2 and/or CD7 warrant further testing for cCD3 to evaluate for T-lineage acute leukemia. Blasts that lack both uniform CD2 and CD7 expression do not require additional cCD3 testing. We propose that CD2 and CD7 could be utilized in a limited antibody flow cytometry panel as a sensitive, robust, and cost-effective way to screen for T-lineage acute leukemia.

Ectopic cervical thymus in children: Clinical and radiographic features

OBJECTIVES

Ectopic thymus is rare and can be a diagnostic challenge. This study evaluated the management of children radiographically diagnosed with ectopic cervical thymus.

METHODS

A retrospective review of 100 patients was performed. Data related to clinical presentation, radiological imaging, pathology, and management were collected. Changes in lesion volume were tracked over time. Clinical characteristics were compared based on lesion location in the neck using analysis of variance modelling.

RESULTS

There were 115 lesions with radiographic features of ectopic cervical thymus (15 children had bilateral lesions). Diagnosis was based on ultrasound in 98% of patients, magnetic resonance imaging in 18%, and computed tomography in 11%. Mean (SD) follow-up duration was 2 (2.2) years. Forty-four percent (51/115) of lesions involved the thyroid gland, 29% (33/115) were in the central neck but separate from the thyroid, 18% (21/115) had mediastinal extension, and 8% (9/115) involved the submandibular region. Location was unclear for two patients. Submandibular lesions were on average 12.4 cm³ larger (95% CI, 8.2, 16.6) than mediastinal lesions at diagnosis, P ≤ .001. Volume of thymic tissue decreased over time, from a mean (standard deviation [SD]) volume of 4.3 cm³ (9.2) at initial ultrasound to 2.7 cm³ (6.1) at final ultrasound (paired t-test, P = .008). Only two patients required surgery: one for compressive symptoms, and the other to rule out malignancy.

CONCLUSION

Ninety-eight percent of children with ectopic cervical thymus were managed conservatively without issues. We propose a classification system based on location to ease communication among clinicians and to help follow these lesions over time.

LEVEL OF EVIDENCE

4, case series Laryngoscope, 130:1577-1582, 2020.