Search

Thymoma is a rare neoplasm of the anterior mediastinum, which originates from the epithelium of the thymic gland; it occurs mainly in middle-aged adults and is much less common in children. The tumor has slow growth and is asymptomatic in most pediatric cases, thus resulting in an accidental discovery; one-third of the young patient presents symptoms related to the compression of the tumor mass on the surrounding anatomic structures and/or related to paraneoplastic syndromes. Surgery is the treatment of choice and complete resection of the thymoma achieves excellent long-term results in terms of disease-free survival. In this article, we report the clinical case of a 21-month-old girl who came to our observation for persistent cough for over a month investigated with a chest X-ray, performed in another hospital. The X-ray showed an extensive opacification of the left hemithorax with contralateral dislocation of the mediastinum. The instrumental investigations carried out in our hospital (ultrasound, computed tomography, and magnetic resonance of the chest) showed a voluminous expansive mass of the left antero-superior mediastinum, which occupied the entire ipsilateral hemithorax and not dissociable from the thymus. At the histologic examination, the mass resulted to be a B1 thymoma with a low degree of malignancy according to the histologic classification of thymic tumors of the World Health Organization.

Background True thymic hyperplasia is a rare condition characterized by enlargement of the thymus while its normal structure is retained. True thymic hyperplasia is known to accompany Graves’ disease, but no association between true thymic hyperplasia and thyroid follicular tumor has been reported so far. We report a case of true thymic hyperplasia in a patient with a thyroid follicular tumor. Case presentation A 52-year-old Japanese man was referred to our hospital for evaluation of a thyroid mass and a mediastinal mass. His serum thyroglobulin level was high, and hemithyroidectomy was performed to remove the thyroid mass. The resected mass was diagnosed as a follicular tumor of uncertain malignant potential. After resection of the thyroid lesion, the patient’s serum thyroglobulin levels were markedly decreased. Seven months later, the patient underwent resection of the mediastinal mass. On pathological examination, the mass was found to consist of lobules, which formed a corticomedullary structure with Hassall’s bodies, indicating a normal thymic mass with hyperplastic thymic tissue, less organized cellular cords, and intermingled adipose tissue. Immunostaining for cytokeratin 19 and cytokeratin 7 indicated that the lesion was consistent with thymic tissue. The lesion was diagnosed as true thymic hyperplasia, and the histological findings suggested that secondary atrophy had occurred. No evidence of recurrence was observed at 24 months after surgery. Conclusions We present a case of a combination of true thymic hyperplasia and thyroidal follicular tumors that, to our knowledge, has not been reported previously. High serum thyroglobulin levels might play a role in hyperplasia of the thymus. Although true thymic hyperplasia is a rare disorder, it should be included in the differential diagnosis of a mediastinal mass in patients with thyroid disease.

Pure red cell aplasia caused by true thymic hyperplasia is extremely rare. We report the case of a 25-year-old female diagnosed with pure red cell aplasia. Following a thymectomy confirming true thymic hyperplasia and corticosteroid therapy, complete response was achieved. Patients diagnosed with pure red cell aplasia should be investigated with a computerized tomographic scan to assess for thymic pathology and if present, this should be resected. Follow-up is essential to monitor for recurrence.

Key Clinical Message A surgical approach is the choice in young infants with MTH, who are furthest from the time of physiological involution of the thymus, and when the thymus achieves the largest relative size, a surgical approach is the choice. Steroid therapy has been shown to be ineffective (4, 9, 16, 18‐20). No surgical complications have been reported, and the outcome is excellent. Recurrence has been seen in only one case.

BACKGROUND True thymic hyperplasia (TTH) is characterized as a distinct increase in both size and weight of thymus, which retains normal microscopic and immunohistochemical appearances. Massive true thymic hyperplasia (MTTH) is an extremely rare but significant subtype of TTH in pediatric ages due to its potentially serious consequences. It was reported that the age of cases with MTTH was predominantly between 1 and 15 years, while those before 1 year rarely occurred. By presenting the diagnosis and treatment process of our case as well as reviewing the related literature, we aimed to analyze the clinical characteristics of MTTH for patients younger than 1 year. CASE A 3-month-old male infant was admitted to our department with a chief complaint of gradually increasing polypnea over 9 days, whose preoperative imaging examination showed a large intrathoracic soft tissue shadow predominantly on the right side. The percutaneous fine-needle biopsy guided by ultrasonography was performed to identify its diagnosis. However, proliferating lymphocytes and Hassall`s corpuscles were seen microscopically in the biopsy tissues, which were immunohistochemically positive for CD3, CD19, CD20, CD99, TdT, PCK and Ki67 ( > 90%). Due to the aggravating symptoms, a second operation with total thymectomy was carried out successfully for this infant, which confirmed the diagnosis of TTH again by both morphological study and immunohistochemical staining from the surgical specimen. CONCLUSIONS By reviewing the literature, there were only 10 cases with MTTH reported between 1975 and 2020 for children aged < 1 year of life, together with our present one. In MTTH patient`s sex had an obviously male predominance (70%). Nine out of 10 presented initial symptoms or signs related to respiratory system and 6 patients showed respiratory distress. All patients were successfully treated by surgical thymectomy without any postoperative complications. The prognosis of MTTH was very successful.

We report a new case of a mediastinal mass in a 19-year-old patient corresponding microscopically to an association of unilocular thymic cyst and true thymic hyperplasia. Our aim is to highlight the absence of specificity of clinical and radiological findings and the necessity of a thorough sampling of the tumor in order to establish the diagnosis.

Introduction: A causal relationship between the thymus gland and myasthenia gravis (MG) has been assumed for decades. However, this relationship is still a matter of conjecture and speculations and awaits definitive proof. Recently, myoid cells have been considered as effectors in the pathogenesis of MG as well as thymic enlargement (thymolipoma, true thymic hyperplasia). Material and methods: we report a retrospective study about 6 cases of thymic enlargement with 4 cases of true thymic hyperplasia (TTH) and 2 cases of thymolipoma (TL). Aim: Our objective is to discuss the role of myoid cells in the pathogenesis of MG associated with thymic enlargement. Results: The majority of our patients were men with a sex ratio of 4/2. Only 2 patients had a past medical history consistent for MG. Myoid cells were found in all cases. Conclusion: Through our small study, the implication of myoid cells in the pathogenesis of the association MG-TL or TTH remains unproved.

中年女性に認められた胸腺過形成の2例を報告する．症例1は46歳，女性．CTで胸腺腫を疑い，胸腔鏡下に腫大した胸腺の生検を施行し，迅速組織診では，反応性リンパ節の診断であった．しかし，永久組織標本では胸腺腫を否定出来ず，胸骨正中切開下に胸腺胸腺腫瘍摘出術を施行した．最終的にリンパ濾胞性胸腺過形成と診断した．症例2は48歳，女性．CTおよびMRIで縦隔腫瘤を指摘された．MRIで腫大した胸腺内に16mm大の結節を認め，こちらは胸腺嚢胞を疑ったが，悪性腫瘍も否定できず，胸骨正中切開下に胸腺胸腺腫瘍摘出術を施行し，真性胸腺過形成および胸腺嚢胞の合併と診断した．自己免疫性疾患の合併を伴わないリンパ濾胞性胸腺過形成や，外傷や化学療法などの治療歴のない非若年者における真性胸腺過形成の報告は極めて稀であるので報告した．

Thymic hyperplasia is a common feature in Graves' disease. However, in most cases, thymic enlargement is minimal, and radiologically detectable massive enlargement of the thymus is infrequently reported. Half of them undergo thymectomy due to the concern about a thymoma. We report a 28-year-old woman with untreated Graves' disease. She had an anterior mediastinal mass that was diagnosed as true thymic hyperplasia by biopsy and disappeared after treatment of the hyperthyroid state. Recognizing the association between thymic hyperplasia and Graves'disease, and existence of the benign course after treatment of the hyperthyroidism may be useful for avoiding unnecessary surgical procedure.

A case of true thymic hyperplasia (TTH) associated with thymic hemorrhage (TH) was observed in a 22-year-old male patient who presented with persistent cough and thoracic pain due to an anterior mediastinal mass. The diagnosis of TTH was supported by the observation that the mediastinal mass was essentially composed of histologically normal thymic lobules with preserved cortico-medullary differentiation. The TTH tissue presented multiple areas of hemorrhage associated with the presence of large, tortuous, abnormal vessels in the thymic stroma. Foci of spindle cell proliferations resembling an epitheliod hemangioma were also seen. This finding raises the possibility that vascular malformations, perhaps due to an abnormal growth of the thymus, may be responsible for some cases of TH associated with TTH.

症例は2歳11ヵ月の男児.出生時特に異常所見はなかったが, 生後3ヵ月の胸部単純X線写真で右上縦隔の拡大を指摘された.その後右上葉無気肺, 肺炎等の呼吸器症状が出現し入退院を繰り返した.胸腺肥大の疑いでステ獄イド負荷療法を2回施行したが, いずれも無反応であった.2歳9ヵ月時, 胸腺腫の疑いで手術を施行した.び漫性に肥大した胸腺を認め胸腺全摘除術を施行した.摘出した胸腺は大きさ10×7×6cm, 重さ210gであった.病理組織は正常胸腺構造を呈し, 観察した範囲内に胚中心の形成はみられなかった.最終診断はTrue thymic hyperplasiaとした.

Thymic hyperplasia describes a nonneoplastic condition of the thymus, characterized by an increased number of the constituent cells of the organ. This concept was initially introduced by Castleman in the late 1940s to define the thymic changes seen in association with myasthenia gravis [1]. Years later, Rosai and Levine [2] in the A.F.I.P. fascicle on “Tumors of the thymus” identified two distinct types of thymic hyperplasia on the basis of histopathologic criteria: true thymic hyperplasia, defined by an increase in the size and weight of the organ that retains a normal microscopic morphology, and lymphoid (or follicular) hyperplasia, characterized by the presence of lymphoid follicles with active germinal centers in the thymic medulla. In the last case, the size and weight of the thymus can be increased, but in most instances they are within normal limits. The term thymitis (or autoimmune thymitis), originally coined by Goldstein in 1966 [3], has been used interchangeably by some authors to denote the lymphoid hyperplasia of the thymus, since its morphological features, both at the light and electron microscopic levels, are markedly similar to those observed in any chronic inflammatory process of other organs [4, 5], being characterized by the presence of peripheral B lymphocytes, lymphoid follicles, and diffuse plasmacytosis.

Massive thymic hyperplasia is an extremely rare form of true thymic hyperplasia most often described in infants and children. Hyperplasia of this order is not known to occur in any other organ, and its etiology and prognostic significance remain unknown. As there is no accurate way of preoperatively differentiating massive thymic hyperplasia from other tumors of the thymus and anterior mediastinum, we advise excision in all cases for histological analysis and relief of mediastinal compression. This description of 4 cases updates the 30 previously reported cases, and includes a literature review.

True thymic hyperplasia and ectopic thymus are very rare in children. In embryologic aspect, thymus is distributed around cervical area and ends up in mediastinum. This case is simultaneous thymic hyperplasia of neck and mediastinum. Ectopic thymus in the neck and thymic hyperplasia in the mediastinum in children were reported 2 and 7 cases respectively in Korea. In Clinical aspects, these thymic hyperplasia were presented by mass. So we should suspect these benign condition to avoid unnecessary operation or biopsy. We report a case of true thymic hyperplasia in the mediastinum with ectopic thymus in the neck in a 4-month-old male infant and review the relevant literature. We believe this is the first reported case in the world of true thymus hyperplasia in the mediastinum with cervical ectopic thymus in the neck

Diffuse thymic hyperplasia following chemotherapy for nodular sclerosing Hodgkin's disease is reported in an 18-year-old woman. The patient's course was complicated by drug-induced pulmonary fibrosis and disseminated herpes zoster. Subsequently she developed genuine diffuse thymic hyperplasia with disappearance of herpes zoster and apparently complete remission of Hodgkin's disease. We stress that restoration of the host immune system, particularly the cell-mediated immunity, is essential for successful control of Hodgkin's disease and the thymic hyperplasia is most likely a favorable sign for it, which should not be confused with recurrence of Hodgkin's disease.

Two cases of massive thymic hyperplasia (MTH) are reported in boys 11 and 14 years of age. Each was detected on routine chest roentgenogram as a large anterior mediastinal mass. Total thymectomy was successfully performed and the two patients were alive and well 9 and 17 years later. The thymectomy specimens weighed 324 and 490 gm, respectively, and had uniform histologic anatomy without lymphoid nodules. Morphometric study documented the massive increase in thymic parenchyma (i.e., true hyperplasia) with retention of a normal proportion of connective tissue expected for age. Since thymic size and structure normally become modified with age, it is essential to consult standard reference data when evaluating hypertrophy and hyperplasia. Gross and histologic features distinguishing MTH from childhood thymoma are discussed.

Huge mediastinal masses in infants are often difficult to diagnose, and thymic enlargement must be considered in each instance, especially when the mass is located anteriorly. In the patient reported on here, the mass occupied approximately 60% of the chest cavity, and surgical intervention was required to establish the precise histological diagnosis. This proved to be massive hyperplastic thymus.

Massive thymic hyperplasia (weight, greater than 100 gm) is a rare lesion in adolescents, and most of the anterior mediastinal masses are true neoplasms. We present a case of massive thymic hyperplasia, in which a 680-gm thymus was resected from a 15-year-old boy. We also present the computed tomographic scan appearance of this lesion, which differed from that previously described, and correlate the histological and radiological findings.

True thymic hyperplasia is rare in adults. The authors have encountered this entity in two patients who were deemed disease-free following combination chemotherapy for malignant disease. It cannot be assumed that the development of a mediastinal mass or its persistence following chemotherapy is due to recurrent or residual disease. The interrelationship between the immunosuppressive effects of neoplasia and chemotherapy with the resultant thymic overgrowth remains to be clarified.

In this report, we describe the clinicopathological features of 4 patients with true thymic hyperplasia. This controversial thymic lesion has only recently been defined as a variable, often massive enlargement of the thymus characterized by a nearly normal microscopic structure. Our study of 4 patients and review of the literature indicate that true thymic hyperplasia has a well-defined clinicopathological profile: prevalence in children or young male patients, absence of associated autoimmune diseases, and often presence of respiratory distress or peripheral blood lymphocytosis, or both. True thymic hyperplasia should be considered in the differential diagnosis of anterior mediastinal masses in children and young adolescents.

Background Thymic enlargement is a common and physiological finding in children and neonates’ X-rays, but it is usually asymptomatic. Occasionally it can cause respiratory distress. In most cases the aetiology of this expansion remains unclear and it is diagnosed as a thymic hyperplasia. True thymic hyperplasia is defined as a gland expansion, both in size and weight, while maintaining normal microscopic architecture. Often it is a diagnosis of exclusion and prognosis is good. Thymic haemorrhage is an unusual condition related to high foetal and neonatal mortality. Case Presentation We report a case of spontaneous massive thymic haemorrhage in a newborn developing at birth acute respiratory distress associated with severe bilateral haemothorax. Thymic enlargement was evident after pleural evacuation and confirmed by radiographic, Computed Tomography (CT) images and Magnetic Resonance Imaging (MRI) sequences. The spontaneous resolution of this enlargement seen with CT scan and MRI sequences suggested a thymic haemorrhage; surgery was not necessary. Conclusion Thymic haemorrhage should be considered in newborn infants with pleural effusion, mediastinal space enlargement and Respiratory Distress.