Thymic Hyperplasia after Adjuvant Chemotherapy in Breast Cancer

A Developing Anterior Mediastinal Mass In A Breast Cancer Patient : Thymic Hyperplasia

INTRODUCTION

True thymic hyperplasia following chemotherapy have been described mostly in children.There are a few cases of thymus hyperplasia have been reported in breast cancer patients . Diagnosis of this unusual entity is very crucial to pretend unnecessary surgery or interventional diagnostic procedures.

CASE PRESENTATION

We report a case of thymus hyperplasia in a patient who was operated and treated with adjuvant chemotherapy for stage 2 breast cancer two years ago. In the follow-up CT scans an anterior mediastinal mass was noted. Radiologic evaluation and follow up revealed thymus enlargement.

DISCUSSION

Thymic hyperplasia following chemotherapy have been described in both children and adults, but occurs mostly in children and adolescents treated for lymphoma and several other types of tumors. Few cases are reported in literature describing thymus hyperplasia following chemotherapy in a breast cancer patient.

CONCLUSION

Radiologists must be aware of this unusual finding in breast cancer patients treated with chemotherapy to guide the clinicians appropriately in order to avoid unnecessary surgical intervention, additional invasive diagnostic procedures, or chemotherapy.

Thymic hyperplasia following double immune checkpoint inhibitor therapy in two patients with stage IV melanoma

Hyperplasia of the thymus is commonly seen in myasthenia gravis and other autoimmune disorders. Thymic size also varies with age, corticosteroid use, infections, and inflammatory disease. Although thymic hyperplasia has been described following chemotherapy, there is no known association of true thymic hyperplasia with immune checkpoint inhibitor therapy. We present two cases of suspected true thymic hyperplasia in patients with stage IV melanoma who were treated with the combination of nivolumab and ipilimumab, which was complicated by immune-related toxicity requiring corticosteroid therapy, and then subsequently also by secondary hypoadrenalism requiring replacement hydrocortisone. In one patient, histological and flurocytometric analyses of an incisional biopsy of the thymus revealed findings consistent with true thymic hyperplasia. In the other case, the stable fluorodeoxyglucose positron emission tomography/Computed tomography (FDG-PET/CT) findings were consistent also with true thymic hyperplasia. These are the first described cases of true thymic hyperplasia following combination immune checkpoint inhibitor therapy for metastatic melanoma. We hypothesize that the true thymic hyperplasia in these cases results from initial lymphocyte depletion caused by intense corticosteroid therapy followed by rebound thymic hyperplasia during the period of relative hypocortisolism, which may have been aggravated by the onset of secondary hypoadrenalism.

[Rebound (reactive) thymic hyperplasia after chemotherapy in children with lymphoma]

INTRODUCTION

Thymic regrowth after chemotherapy treatment has been reported in children with lymphoma, and in order to avoid misdiagnosing these cases as relapses, physicians should become familiar with rebound (reactive) thymic hyperplasia (RTH) and remain aware of its possible occurrence. We aimed to estimate the prevalence of RTH in children with lymphoma after completion of chemotherapy and to evaluate the clinical characteristics, outcomes, and the findings of computed tomography (CT) and gallium-67 (GA-67) scans in these patients.

PATIENTS AND METHODS

We conducted a retrospective cross-sectional study by reviewing the health records of children with a lymphoma diagnosis managed at an outpatient paediatric oncology clinic in Jeddah, Saudi Arabia.

RESULTS

Rebound thymic hyperplasia was detected in 51.9% of the lymphoma patients (14/27). It developed a median of 2.5 months after completion of chemotherapy (range, 2.0-4.25 months). Patients with RTH had significantly shorter treatment durations, and we found no significant differences between patients with and without RTH in sex, age at diagnosis, type of lymphoma or type of treatment received. All patients with RTH were asymptomatic, and routine laboratory tests did not detect any abnormalities in them. The findings of CT and GA-67 scans were highly suggestive of RTH. None of the patients with RTH had a recurrence, and RTH resolved spontaneously within a median of 6 months (range, 4.0-11.0).

CONCLUSION

RTH was detected in ∼50% of children with lymphoma after completion of chemotherapy. A clinical evaluation and laboratory tests combined with imaging by CT and GA-67 can help identify RTH and rule out other lesions elsewhere.

Rebound Thymic Hyperplasia after Chemotherapy in Children with Lymphoma

BACKGROUND

Development of mediastinal masses after completion of chemotherapy in pediatric patients with malignant lymphoma is worrisome and challenging to clinicians.

METHODS

We performed a retrospective review of 67 patients with lymphoma treated at our hospital from January 1, 2001 to June 1, 2013. Patients who received at least two chest computed tomography (CT) examinations after complete remission (CR) was achieved were further analyzed. Gallium-67 scans and positron emission tomography (PET) were recorded and compared between these patients.

RESULTS

Sixty-two of 67 patients reached CR, of whom 31 (22 male, 9 female) were patients that received at least two chest CT examinations after CR. Rebound thymic hyperplasia (RTH) was diagnosed in 21/31 patients (67.7%), including 14/23 (60.9%) and seven out of eight (87.5%) with non-Hodgkin's lymphoma and Hodgkin's lymphoma, respectively. Ages ranged from 3 years to 18 years (median 10 years). Increased radioactivity uptake of the anterior mediastinum in gallium scans was found in nine out of 20 patients (45%) with thymic rebound. PET was performed in six out of 21 patients. Increased fluorodeoxyglucose (FDG)-avid uptake in the anterior mediastinum was observed in four of six patients (66.7%) by PET. One patient received thymectomy. No patients with RTH had lymphoma relapse within the median follow-up period (5 years). Relapse was statistically significantly different (p = 0.001) between patients with and without RTH.

CONCLUSION

RTH developed in 67.7% of pediatric patients with lymphoma in CR after chemotherapy. The association of RTH development and lowered relapse rates has yet to be determined. Awareness of this phenomenon is important in the prevention of unnecessary surgical intervention or chemotherapy.

The Thymus in Experimental Mammary Carcinogenesis and Polychemotherapy

Histological study of structural transformations in the thymus of Wistar females in induced carcinogenesis (N-methyl-N-nitrosourea injection in the right 2-nd mamma) and polychemotherapy (6 months after tumor growth initiation; cyclophosphamide, methotrexate, and 5-fluorouracyl) was carried out. The area of the cortical matter in the thymus decreased 6 months after carcinogenesis induction, the percentage of connective tissue elements and glandular tissue and the counts of immunoblasts and cells with pyknotic nuclei increased, this indicating the development of accidental involution of the thymus. Animals of the experimental tumor+chemotherapy group exhibited morphological signs of lymphocyte migration from the thymus and suppressed activities of the lymphoid and epithelial components (lesser area of connective tissue elements and glandular tissue, lesser density of parenchymatous cell elements, lesser counts of immunoblasts and small lymphocytes, and larger area of the medulla) in comparison with animals without chemotherapy.

Thymic hyperplasia after chemotherapy in adults with mature B cell lymphoma and its influence on thymic output and CD4(+) T cells repopulation

To investigate the thymic regenerative potential in adults accepting chemotherapy for lymphoma. The dynamics of thymic activity in 54 adults from baseline to 12 mo post-chemotherapy was analyzed by assessing thymic structural changes with serial computed tomography (CT) scans, and correlating these with measurements of thymic output by concurrent analysis of single-joint (sj) T-cell receptor excision circles (sjTREC) and CD31⁺ recent thymic emigrants (RTE) in peripheral blood. Furthermore, the consequence of thymic renewal on peripheral CD4⁺ T cell recovery after chemotherapy was evaluated. Time-dependent changes of thymic size and thymic output assessed by both sjTREC levels and CD31⁺ RTE counts in peripheral blood were observed during and after chemotherapy. Enlargement of thymus over baseline following chemotherapy regarded as rebound thymic hyperplasia (TH) was identified in 20 patients aged 18−53 y (median 33 y). By general linear models repeated measure analysis, it was found that, patients with TH (n = 20) had a faster recovery of sjTREC levels and CD31⁺ RTE counts after chemotherapy than patients with comparable age, gender, diagnosis, disease stage, thymic volume and output function at baseline but without TH (n = 18) (p = 0.035, 0.047); besides, patients with TH had a faster repopulation of both naïve CD4⁺ T cell and natural regulatory CD4⁺ T cell subsets than those without TH (p = 0.042, 0.038). These data suggested that adult thymus retains the capacity of regeneration after chemotherapy, especially in young adults. The presence of TH could contribute to the renewal of thymopoiesis and the replenishment of peripheral CD4⁺ T cell pool following chemotherapy in adults.

Incidentally Visualization of the Thymus on Whole-Body Iodine Scintigraphy: Report of 2 Cases and Review of the Latest Insights

Radioiodine uptake is not commonly seen by the thymus gland. On the contrary, the gland is slowly replaced by fat after puberty. Herein, we present 2 patients with papillary thyroid carcinoma, follicular variant, and cervical lymph node involvement. After total/near-total thyroidectomy, the patients received I for ablation therapy. On posttreatment radioiodine scintigraphy, mediastinal I uptake was noted that finally was histologically/anatomically diagnosed as thymus gland uptake. It should be borne in mind as a potential cause of false-positive whole-body I scintigraphy.

Mediastinal mass following successful chemotherapy for ovary dysgerminoma: benign process or disease relapse? A case report

BACKGROUND

Ovarian dysgerminoma is a rare tumor that affects adolescent girls and young women. Due to its high radio-chemosensitivity, prognosis is normally excellent. Relapses occur in less than 20% of early stage disease, but are more frequent in advanced disease. It is known that some benign mediastinal processes may mimic tumor relapse, particularly in young patients. This is the case of physiologic thymic hyperplasia, which occurs as a rebound phenomenon after chemotherapy in young women with ovarian dysgerminoma. Until now, no cases of dysgerminoma with benign mediastinal mass have been published.

CASE

A young woman with bulky ovarian dysgerminoma, who obtained complete disease remission after chemotherapy, subsequently developed a mediastinal mass which was initially confused with a mediastinal relapse. CT scan features (close thymic location, homogeneous hypodensity, absence of infiltration of mediastinal structures) and subsequent PET/CT scan (homogeneous glucose uptake and a typical inverted V morphology) supported the diagnosis of thymic hyperplasia. No further invasive procedures were performed. 34 months from the diagnosis the patient is in good physical condition with no signs of relapse.

CONCLUSIONS

Our case underlines the importance of knowing the age- and treatment-related incidence of physiologic thymic hyperplasia in young women with ovarian dysgerminoma in order to reduce the potential pitfalls and to avoid unnecessary invasive diagnostic procedures.

Clinical analysis of thymic regrowth following chemotherapy in children and adolescents with malignant lymphoma

OBJECTIVES

Thymic regrowth following chemotherapy has typical clinical and imaging manifestations that can be used to diagnose it prior to pathological diagnosis. We investigated methods for diagnosing thymic regrowth following chemotherapy with non-invasive methods.

METHODS

Our study included 26 children and adolescents with thymic regrowth following chemotherapy for malignant lymphoma. Computed tomography scans were routinely performed for follow-up observations. After the emergence of new mediastinal masses, patients either underwent Fluorine-18 fluorodeoxyglucose-positron emission tomography scans to identify the characteristics of the mass, or were closely followed up.

RESULTS

Thymic regrowth occurred 1-12 months after the last chemotherapy (mean, 4 months). Computed tomography mostly revealed diffusely enlarged thymic parenchymatous tissues that maintained normal thymic morphology. Computed tomography values were 36.72 ± 9.48 Hu and increased by 5.56 ± 2.62 Hu in contrast enhancement. The mean volume of the mass was 19.2 cm(3). Twenty patients underwent positron emission tomography; among them, five (25%) showed no intake of Fluorine-18 fluorodeoxyglucose in the anterior mediastinal mass, and 15 (75%) showed radioactivity distribution in the mass with a mean standardized uptake value of 2.7; the shape was regular and radioactivity distribution was uniform. The mean follow-up duration was 40 months and all patients achieved disease-free survival.

CONCLUSIONS

In the absence of pathological diagnosis, thymic regrowth following chemotherapy can be diagnosed by clinical features combined with characteristic manifestations in computed tomography and positron emission tomography scans.

Radioiodine concentration by the thymus in differentiated thyroid carcinoma: report of five cases

The radioactive iodine has been used with great value as a diagnostic and therapeutic method in patients with differentiated thyroid carcinoma previously submitted to total thyroidectomy. False-positive whole-body scans may occur due to misinterpretation of the physiologic distribution of the radioisotope or lack of knowledge on the existence of other pathologies that could eventually present radioiodine uptake. Thymic uptake is an uncommon cause of false-positive whole-body scan, and the mechanism through which it occurs is not completely understood. The present paper reports five cases of patients with differentiated thyroid cancer who presented a mediastinum uptake of radioiodine in a whole-body scan during follow-up. The patients had either histological or radiological confirmation of the presence of residual thymus gland. It is very important to know about the possibility of iodine uptake by the thymus in order to avoid unnecessary treatment, such as surgery or radioiodine therapy.

[Filling the thymic space after treatment of Hodgkin's disease: rebound or relapse]

We report the case of a 36-year-old women with Hodgkin's disease treated with polychemotherapy and bone marrow autograft. Progressive growth of a thymic mass suggested possible relapse four months after treatment withdrawal. This mass did not exhibit gallium-67 uptake but showed strong affinity for 18-FDG (SUV=6.8). Surgical biopsy ruled out recurrence of Hodgkin's disease of the thymus and led to the diagnosis of thymic rebound. The aspect of the thymic compartment returned to normal spontaneously at one year.