Spindle epithelial tumor with thymus-like differentiation (SETTLE) of the thyroid

Single-cell RNA Sequencing Analysis Reveals New Immune Disorder Complexities in Hypersplenism

Hypersplenism (HS) is a concomitant symptom of liver or blood disease. Not only does the treatment of HS face challenges, but the transcriptome of individual cells is also unknown. Here, the transcriptional profiles of 43,037 cells from four HS tissues and one control tissue were generated by the single-cell RNA sequencing and nine major cell types, including T-cells, B-cells, NK cells, hematopoietic stem cells, neutrophil cells, mast cells, endothelial cells, erythrocytes, and dendritic cells were identified. Strikingly, the main features were the lack of CCL5+ B-cells in HS and the presence of SESN1+ B cells in HS with hepatocellular carcinoma (HS-HCC). In cell-cell interaction analysis, CD74-COPA and CD94-HLA-E in HS were found to be up-regulated. We further explored HS-specifically enriched genes (such as FKBP5, ADAR, and RPS4Y1) and found that FKBP5 was highly expressed in HCC-HS, leading to immunosuppression. Taken together, this research provides new insights into the genetic characteristics of HS via comprehensive single-cell transcriptome analysis.

Spindle cell tumour with thymus-like differentiation (SETTLE) on fine needle aspiration cytology: A case report highlighting diagnostic pitfalls

A 7-year-old girl presented with a painless neck swelling localised near the left lobe of the thyroid gland, which was initially investigated by fine needle aspiration cytology. This raised a differential diagnosis of medullary thyroid carcinoma and small round blue cell tumour. Only after several additional clinical investigations and a total thyroidectomy was a definitive diagnosis of spindle cell tumour with thymus-like differentiation (SETTLE) reached. This case report highlights how contemporaneous clinical and investigation findings made arriving at a definitive diagnosis challenging, contributed to diagnostic delay, and ultimately influenced choice of treatment.

Spindle Epithelial Tumor of Thymus-like Differentiation (SETTLE) in a 3-year-old African girl

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare tumor of the thyroid gland occurring in children and young adults. This report presents SETTLE as a tumor that can also affect young children (under fives). Although majority of the reports were in Caucasians, the tumor can affect all races.

Spindle Epithelial Tumor with Thymus-Like Differentiation (SETTLE): A Next-Generation Sequencing Study

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a malignant biphasic neoplasm of the thyroid or neck with propensity for late metastasis. Unlike synovial sarcoma, its main morphologic mimic, SETTLE lacks synovial sarcoma-associated translocations. A single case of SETTLE has shown a KRAS mutation but to date no comprehensive next generation sequencing studies of this rare neoplasm have been undertaken. Herein, we subjected 5 well defined cases of SETTLE to direct sequence analysis of 592 genes and fusion gene analysis of 52 genes frequently rearranged in human cancers. We identified one case with two pathogenic variants in the KMT2D gene, one being in an intron splice site (c.674-1A>G) and the other being a frameshift variant (p.M2829fs). This same case also had a pathogenic nonsense variant in the KMT2C gene (p.R1237*). A second case of SETTLE carried a pathogenic NRAS missense variant, Q61R. No other molecular alterations, microsatellite instability, gene fusions or amplifications were identified.

Spindle epithelial tumor with thymus-like differentiation (SETTLE): clinical-pathological features, differential pathological diagnosis and therapy

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a very rare tumor of the thyroid gland. An algorithm for the diagnosis and treatment of SETTLE has yet to be established. The aim of this study was to identify all case reports of SETTLE and to compare the clinical-pathological features and therapy of the cases identified. We performed a PubMed search for case reports of SETTLE in English published up to November 2014 in which "SETTLE" and "Spindle epithelial tumor with thymus-like differentiation" were keywords. We identified 35 articles for a total of 42 cases. We found that SETTLE usually occurs in children and adolescents as an asymptomatic neck mass. Thyroid function tests and tumor markers are invariably within normal range in all patients, and fine needle aspiration biopsy is rarely diagnostic for SETTLE. All 42 patients had undergone thyroidectomy. After surgical resection, chemotherapy (adjuvant or first/second-line treatment) and/or radiotherapy were administered to control tumor growth in cases with metastatic involvement. Although SETTLE presents a low-grade malignancy, it can metastasize to lymph nodes, the mediastinum, lung, vertebrae, and kidney even many years after the initial diagnosis. SETTLE may have a good prognosis if appropriately treated at initial presentation and if patients undergo long-term monitoring with regular clinical and morphological evaluations.

Intrathyroidal ectopic thymic tissue mimicking thyroid cancer in children

OBJECTIVE

To increase awareness of the important differential diagnosis between thyroid cancer and intrathyroidal ectopic thymic tissue when performing neck ultrasound (US) in pediatric patients.

METHODS

We report 2 cases of intrathyrodal thymic tissue that were initially referred as possible papillary thyroid cancer (PTC). US and cytologic features of these lesions are described, and the distinguishing US characteristics of intrathyroidal thymic tissue versus PTC are discussed.

RESULTS

Two pediatric patients who underwent thyroid US were diagnosed with thyroid nodules suggestive of PTC. The suspected lesions in both patients exhibited an echo texture identical to the normal thymus gland. Fine-needle aspirate (FNA) biopsy of the nodule in the first case revealed numerous lymphocytes with positive immunocytochemical staining for CD3, confirming a T cell phenotype. The second patient underwent follow-up US imaging 8 months later that showed stability of the intrathyroidal nodule.

CONCLUSION

Intrathyroidal ectopic thymic tissue can be mistaken for PTC as both conditions have similar US features. Increased awareness of this unique mimicry may help to avoid unnecessary invasive investigations and surgery in these young patients.

Thyroid spindle epithelial tumor with thymus-like differentiation (SETTLE): case report and review

Spindle epithelial tumor with thymus-like element (SETTLE) is a rare malignant neoplasm of the thyroid, occurring predominantly in children, adolescents, and young adults. SETTLE usually presents itself as a thyroid mass, without metastases at diagnosis. It is believed to derive from branchial pouch or thymic remnant tissue showing primitive thymic differentiation. This article reports the clinical, cytological, histological and immunohistochemical features of a SETTLE in a 3-year-old girl. Microscopic exam revealed a nodular, highly cellular neoplasm displayed in the classic biphasic pattern, with mixture of prominent spindle cell component and a minor glandular component lined by mucinous or respiratory-type epithelium. The immunohistochemical study showed strong and diffuse positivity for pan-CK, vimentin and smooth muscle actin. The present case is the first SETTLE case reported in Brazil. To date, the patient described remains without evidence of recurrence or metastasis 5 years after surgery.

Spindle epithelial tumor with thymus-like differentiation: a morphologic, immunohistochemical, and molecular genetic study of 11 cases

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is an extremely rare tumor of the thyroid and neck, first described by Chan and Rosai. SETTLE is a low-grade malignancy, with potential for late lung, lymph node, and other visceral metastases. The clinicopathologic features of SETTLE overlap significantly with those of synovial sarcoma. Thirteen cases previously diagnosed as "SETTLE" (11 cases) or "malignant neoplasm-SETTLE versus synovial sarcoma" (2 cases), were retrieved. Immunohistochemistry for low-molecular-weight cytokeratins, high-molecular-weight cytokeratins, cytokeratin 7, cytokeratin 20, epithelial membrane antigen, bcl-2, CD34, CD99, CD117, INI-1, and TLE1 were performed. Reverse transcriptase polymerase chain reaction for the SS18/SSX1 and SS18/SSX2 fusion genes and fluorescent in-situ hybridization for SYT rearrangement was performed. The 11 cases diagnosed, as "SETTLE" were negative for synovial sarcoma-associated fusion genes, whereas the other 2 cases were positive. SETTLE occurred in 7 females and 4 males (7 to 50 y of age, median 13.5 y) and involved the thyroid gland in 10 cases. Clinical follow-up showed 3 patients to be disease-free 7, 10, and 15 years after surgery. One patient had a lymph node metastasis at diagnosis and lung metastases 14 months after diagnosis. SETTLE infiltrated the thyroid, and consisted of a vaguely nodular admixture of fascicular, reticular, hyalinized, and microcystic areas. Spindled zones blended imperceptibly into areas showing epithelial differentiation, in the form of glomeruloid glandular structures, sertoli-like tubules, and small glands, lined by cuboidal to columnar cells. Mitotic activity was very low, necrosis was absent, and pleomorphism was not present. By immunohistochemistry, SETTLE showed extensive expression of high-molecular-weight cytokeratins in 7 of 8 cases (88%). Expression of low-molecular-weight cytokeratins and epithelial membrane antigen was limited, confined to only scattered cells in 7 of 8 (88%), and 4 of 8 (50%) of cases, respectively. Cytokeratin 7 expression was more widespread (7 of 8 cases, 88%). Cytokeratin 20 was negative. Expression of CD99 and bcl-2 was seen in 6 of 8 (75%) and 7 of 8 (88%) cases, respectively. CD117, INI-1, and TLE1 expression was seen in 6 of 8 (75%), 8 of 8 (100%), and 1 of 5 (20%) of cases, respectively. We conclude that traditional morphologic study and a limited panel of ancillary immunostains are sufficient for the distinction of SETTLE from synovial sarcoma in almost all instances. Molecular genetic study may, however, be helpful in selected cases, particularly in limited biopsies.

A six-year-old boy with a suspicious thyroid nodule: intrathyroidal thymic tissue

BACKGROUND

Ectopic intrathyroidal thymus tissue that forms mass lesions as a consequence of aberrant thymic migration during embryogenesis is rarely reported in the literature.

METHODS

We present the case of a 6-year-old boy with a right thyroid nodule and bilateral cervical lymph nodes. Thyroid hormone, antibodies, and routine chemistry tests were normal. Real-time thyroid ultrasound showed a right calcified nodule measuring 8 x 5 x 7 mm and multiple bilateral cervical lymph nodes. I131 scan showed mild decreased uptake in the right upper lobe. On fine-needle aspiration biopsy we discovered an atypical lymphoid proliferation that was suspicious, although not diagnostic, of a lymphoma. Immunostain for calcitonin was negative. Flow cytometry of the thyroid nodule aspirate demonstrated an abnormal polyclonal T cell population with dual expression of CD4 and CD8, and a subpopulation of cells that expressed TdT suggesting the possibility of lymphoblastic lymphoma. DNA analysis, as well as polymerase chain reaction for T cell and B cell gene rearrangement, did not demonstrate changes in the gene for the heavy chain of immunoglobulin of B cells and gamma chain of the T cell receptor. Lymph node aspirate showed unremarkable T and B lymphoid cells.

MAIN OUTCOMES

The diagnosis of ectopic intrathyroidal thymus was made after the operation.

CONCLUSION

Ectopic thymus tissue should be considered in the differential diagnosis of thyroid masses, especially in children.

Unusual spindle cell tumor of thyroid (SETTLE)

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare tumor seen mostly in children and adolescents. It is presumed that it arises from ectopic thymus or remnants of branchial pouches that differentiate along the thymic line. Unusual spindle cell-predominant histology makes this entity difficult to recognize. The clinical course is not exactly known due to the small number of reported cases but metastasis has been documented during initial presentation. We report a case of SETTLE in the neck where preoperative clinical and radiological impression was that of a mass in the left submandibular gland area. However, during the operation it was felt by the surgeon that the mass was in continuity with the left thyroid lobe.

Fine-needle aspiration biopsy of monophasic variant of spindle epithelial tumor with thymus-like differentiation of the thyroid: report of one case and review of the literature

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a rare biphasic tumor of the thyroid with approximately 20 well-documented cases reported in the English literature. Although a monophasic variant of SETTLE is conceivable, the majority of the reported cases were truly biphasic tumors. A minimal amount of epithelial component was present in the reported cases of so-called spindle-cell predominant SETTLE. Here, we report an apparently monophasic case of SETTLE in a 16-yr-old girl, in which no epithelial cells were identified in either fine-needle aspiration biopsy (FNAB) or the subsequent hemithyroidectomy specimen. The FNAB smears were moderately cellular and composed of single and loosely grouped spindle cells with homogenous metachromatic material, which could be mistaken as amyloid, erroneously suggesting medullary thyroid carcinoma. The compact nodules of uniform spindle cells in histology sections raised the possibility of monophasic synovial sarcoma. The spindle cells stained positive for both cytokeratin and vimentin, but were negative for thyroglobulin and calcitonin as well as neuroendocrine markers, confirming the diagnosis of SETTLE.

Spindle epithelial tumor with thymus-like differentiation (SETTLE): Youngest reported patient

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is a very rare thyroid tumor. It is one of a family of tumors arising either from ectopic thymus or remnants of branchial pouches that retain the potential to differentiate along the thymic line. Herein is reported a case of SETTLE in a 2-year-old girl. The patient underwent right thyroid lobectomy for a tumor of the right thyroid lobe. The resected specimen of this tumor revealed a whitish and solid mass. On microscopy, the tumor exhibited an area of spindle cells, glandular epithelium, and mucinous cystic lesions. The following findings were obtained on immunohistochemistry: the spindle cell area was diffusely positive for cytokeratin AE1/3 and vimentin, and partially positive for alpha-smooth muscle-specific actin. The glandular structures consisted of columnar cells and the cystic area was also positive for cytokeratin AE1/3. All three components of the tumor were negative for thyroglobulin, thyroid transcription factor-1, S-100 protein, carcinoembryonic antigen, somatostatin, synaptophysin, and chromogranin A. On the basis of the aforementioned findings, SETTLE was diagnosed. The patient remains disease free to date, 2 years after surgery with no additional treatment. To the best of the authors' knowledge the present SETTLE patient is the youngest yet reported.

Early metastasizing spindle epithelial tumor with thymus-like differentiation (SETTLE) of the thyroid

Spindle epithelial tumor with thymus-like elements is a rare thyroid lesion of children and young adults thought to be derived from branchial pouch remnants or foci of ectopic thymus. The lesion is poorly understood, and although it was originally believed to follow an indolent clinical course, its potential for late metastasis is becoming generally acknowledged. We have recently seen a unique case of this rare tumor in an 11-year-old boy, in which an unexpected and salient feature is the presence of a micrometastasis in a single lymph node at presentation. With the exception of 1 case with extensively infiltrative tumor and metastatic disease at the time of onset, in all other cases dissemination occurred years after surgical resection of the primary lesion. We review all previously reported cases and provide a detailed study of the histologic and ultrastructural appearances of this lesion.

Spindle epithelial tumor with thymus-like differentiation (SETTLE) of the thyroid with neck lymph node metastasis: a case report

Spindle epithelial tumor with thymus-like differentiation (SETTLE) is an extremely rare type of thyroid tumor. It has been reported only 20 times in the English literature. This tumor occurs predominantly in young patients and has a protracted clinical course despite the occurrence of metastases. In the recent literature SETTLE has been considered to be a tumor of low malignant potential with distant metastases developing some years after diagnosis. Herein we report a case of SETTLE in a 22-yr-old man in which a lymph node metastasis developed soon after the primary tumor manifestation. Histological examination of the tumor showed the predominantly monophasic variant of SETTLE. The primary and metastatic lesions were highly cellular tumors composed of sheets of spindle cells that were positive for pan-cytokeratin and vimentin and negative for thyroglobulin, calcitonin, and S-100 protein.