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

Abstract

SUMMARYSpindle 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. Arq Bras Endocrinol Metab. 2010;54(7):657-62 SUMÁRIO O tumor epitelial de células fusiformes com elemento thymus-like é uma rara neoplasia maligna da tireoide, ocorrendo predominantemente em crianças, adolescentes e adultos jovens. Habitualmente, esse tumor se apresenta como massa tireoideana, sem metástases ao diagnóstico. Acredita-se derivar de arco branquial ou tecido remanescente tímico, apresentando diferenciação tímica primitiva. Este artigo descreve os aspectos clínicos, citológicos, histológi-cos e imuno-histoquímicos de um caso de SETTLE diagnosticado em uma menina de 3 anos de idade. O aspecto microscópico encontrado no tumor foi de uma lesão nodular, hipercelular, disposta em aspecto bifásico clássico, com componente de células fusiformes, e de tecido glandular acompanhado por epitélio mucinoso e respiratório. O estudo imuno-histoquímico foi positivo para pan-CK, vimentina e actina de músculo liso. Esse caso é o primeiro relato de SETTLE no Brasil. A paciente descrita permanece sem evidência de doença em atividade cinco anos após o tratamento cirúrgico. Arq Bras Endocrinol Metab. 2010;54(7):657-62

Spindle epithelial tumor with thymus-like differentiation of the thyroid in a 70-year-old man

“…SETTLE is considered to be a low grade malignant neoplasm due to its indolent growth, protracted clinical course, and tendency to develop delayed blood-borne metastasis [ 8 ]. Owing to this tendency, long-term follow-up following the treatment of the lesion is essential and close attention is required at the time of the initial diagnosis.…”

Spindle epithelial tumor with thymus-like differentiation: A case report and comprehensive review of the literature and treatment options

“…We identified 41 published cases of SETTLE in the literature, which are listed in Table along with the new case described above . SETTLE predominantly affects children and young adults.…”

When to settle for SETTLE! A lesson learned from our cases

“…SETTLE, which is described as a low grade malignant tumor with a favourable prognosis after complete surgical resection, can have an aggressive course in some cases [ 5 ]. SETTLE patients have long survival despite the development of metastasis [ 38 ].…”