Primary mediastinal large-B-cell lymphoma: radiologic findings at presentation

Review of clinical and diagnostic imaging of the thymus: from age-related changes to thymic tumors and everything in between

The thymus, a primary lymphoid organ of the immune system, undergoes several changes due to a variety of reasons, ranging from aging to pathological conditions. These changes can make distinguishing between benign and neoplastic changes in the thymus challenging, thereby complicating the histopathological diagnoses of thymic tumors. Moreover, most patients with thymic tumors are asymptomatic at the time of diagnosis. Therefore, imaging plays an extremely important role in the evaluation of thymic lesions. In this review, we introduced the imaging characteristics of the thymus, ranging from benign findings, such as normal maturation and benign lesions, to neoplasms.

Thymic Parenchymal Hyperplasia

Thymic hyperplasia is a rare condition generally caused by lymphoid follicular hyperplasia associated with autoimmune disorders. True thymic parenchymal hyperplasia unassociated with lymphoid follicular hyperplasia is extremely rare and may give rise to difficulties in diagnosis. We have studied 44 patients with true thymic hyperplasia (38 females and 6 males) aged 7 months to 64 years (mean, 36 years). Eighteen patients presented with symptoms of chest discomfort or shortness of breath; in 20 patients, the lesions were discovered incidentally. Imaging studies demonstrated enlargement of the mediastinum by a mass lesion suspicious for malignancy. All patients were treated with complete surgical excision. The tumors measured from 3.5 to 24 cm (median, 10 cm; mean, 10.46 cm). Histologic examination showed lobules of thymic tissue displaying well-developed corticomedullary architecture, with scattered Hassall corpuscles separated by mature adipose tissue and bounded by a thin fibrous capsule. No cases showed evidence of lymphoid follicular hyperplasia, cytologic atypia, or confluence of the lobules. Immunohistochemical studies showed a normal pattern of distribution for keratin-positive thymic epithelial cells against a background rich in CD3/TdT/CD1a+ lymphocytes. Twenty-nine cases had an initial clinical or pathological diagnosis of thymoma or thymoma vs thymic hyperplasia. Clinical follow-up in 26 cases showed that all patients were alive and well between 5 and 15 years after diagnosis (mean, 9 years). Thymic parenchymal hyperplasia causing significant enlargement of the normal thymus that is sufficient to cause symptoms or worrisome imaging findings should be considered in the differential diagnosis of anterior mediastinal masses. The criteria for distinguishing such lesions from lymphocyte-rich thymoma are presented.

[Lesions of the prevascular mediastinum]

CLINICAL/METHODOLOGICAL ISSUE

Mediastinal masses are a group of heterogenous lesions which may be a coincidental finding or present with symptoms. More than half of mediastinal lesions are located in the prevascular mediastinum. As these tumors are not often encountered in clinical routine, making a diagnosis with a high degree of confidence may seem challenging.

STANDARD RADIOLOGICAL METHODS

The latest computed tomography (CT)-based classification of the mediastinal compartments by the International Thymic Malignancy Interest Group (ITMIG) moves away from earlier radiograph-based classification systems and helps to reliably classify tumors based on location, although in some cases the lesion can occupy more than one compartment.

PERFORMANCE

Radiology plays an important role in the evaluation of anterior mediastinal lesions. Although in some cases imaging features alone allow a diagnosis to be made; in other cases knowledge of important radiological features and their analysis in the context of patient factors like age and duration of symptoms can help to narrow down the differential diagnosis, avoid unnecessary workup, and guide further steps.

PRACTICAL RECOMMENDATIONS

Computed tomography (CT) is central for the characterization of mediastinal masses in clinical routine. In some situations, like in the case of thymic cysts or thymic hyperplasia, magnetic resonance imaging (MRI) can be used as a noninvasive problem-solving tool.

Case Report: Primary Mediastinal Large B-Cell Lymphoma Invasion of Extranodal Thyroid Tissue Mimicking Tuberculosis and Confounded by Similar Ultrasonic Appearance

Background

Primary mediastinal large B-cell lymphoma (PMBCL) is a rare type of diffuse large B-cell lymphoma, which has significant features that overlap with those of Hodgkin’s lymphoma. Ultrasound is a commonly used modality to characterize superficial lymph no5des, and ultrasonic findings are often used to distinguish lymphoma from lymph node tuberculosis in daily clinical practice. Although a common malignancy, lymphoma rarely involves extranodal tissues.

Case Presentation

Here we report the case of a 42-year-old Chinese male patient with PMBCL who was misdiagnosed with tuberculosis because of extranodal invasion. He visited our hospital for a neck mass that he had been noting for 1 week. Ultrasound revealed multiple enlarged lymph nodes on both sides of the neck. The lesions appeared to involve the surrounding soft tissue and thyroid gland, resembling a tuberculous sinus tract formation. Cervical spine computed tomography showed no obvious abnormalities in the cervical cone or bone damage. Contrast-enhanced ultrasound indicated that one of the enlarged lymph nodes in the right neck was rich in blood supply and exhibited centripetal enhancement, with uniform high enhancement at the peak. The patient underwent two ultrasound-guided punctures; the first puncture was performed for an enlarged lymph node in the right neck at Hangzhou Red Cross Hospital. Hodgkin’s lymphoma was suspected based on pathological and immunohistochemical findings, whereas a rare type of diffuse large B-cell lymphoma was suspected at Zhejiang Cancer Hospital.

Conclusions

Lymphoma is often misdiagnosed, causing delayed treatment initiation and affecting patient outcomes as the disease progresses. The present case demonstrates that the ultrasonic appearance of lymphoma may sometimes be confused with that of tuberculosis. Although ultrasound-guided needle biopsy has a high diagnostic accuracy, it may also cause diagnostic deviation because of insufficient sampling volume. Moreover, owing to the enlargement of multiple lymph nodes due to lymphoma or lymph node tuberculosis, puncturing different lymph nodes may provide different results.

Expecting the unexpected - Primary mediastinal large B cell lymphoma presenting as huge lung parenchymal mass

The first possibility considered in the etiology of large lung masses is neoplastic lesions. The differential diagnoses of these masses include bronchogenic carcinoma, pulmonary sarcoma, primitive neuroectodermal tumor etc. Primary or secondary pulmonary parenchymal lymphomas presenting as large mass is distinctly rare. We share the case of a young lady who presented with a large left lung mass almost entirely replacing the left lung parenchyma, with associated intrathoracic lymphadenopathy. On evaluation she was proved to have primary mediastinal large B-cell lymphoma. Treatment with an aggressive chemotherapy regimen led to complete remission of the parenchymal and nodal disease. The uncommon radiological presentation and the excellent therapeutic response despite huge tumor load merit clinical attention.

[Lung involvement in hematologic systemic diseases]

Pulmonary diseases can occur across the entire disease spectrum of malignant hematologic systemic diseases. Although infectious processes of the lungs are common in these immunosuppressed patient collectives, noninfectious causes account for up to half of the pulmonary manifestations found in hematologic malignancies. Besides the frequent infections including opportunistic pathogens, a broad differential diagnosis including drug-induced lung injury by cytostatic substances, cytokines, and innovative immunotherapeutic agents, rarer transfusion of blood products and intrathoracic manifestations of the hematologic malignancy itself, have to be kept in mind. Finally, vascular complications can also lead to pulmonary reactions. Early and consistent diagnostics and treatment of the bronchopulmonary, intrathoracic and vascular complications within the framwework of hematologic systemic diseases can be essential for the patient's prognosis.

Primary Mediastinal Large B-Cell Lymphoma: A Review for Radiologists

OBJECTIVE. The purpose of this article is to provide a primer for radiologists focused on integrating the radiologic, pathologic, and clinical features of primary mediastinal large B-cell lymphoma (PMLBCL). CONCLUSION. PMLBCL is a unique subtype of lymphoma that poses diagnostic and therapeutic challenges to the fields of radiology and oncology. Knowledge of this distinctive clinical-pathologic entity and its associated imaging and clinical features is critical for radiologists.

Small cell lung cancer mimicking lymphoma in CT and 68Ga-DOTA-NOC PET/CT: A case report

RATIONALE

Small cell lung cancer accounts for 15-20% of all lung cancers and is the most common pulmonary neuroendocrine neoplasm. Most small cell lung cancers arise from lobar or main bronchi, the most common manifestations of small cell lung cancer is a large mass centrally located within the lung parenchyma or a mediastinal mass involving the hilus. Small cell lung cancer is easily ignored by clinicians without lung parenchyma and hilus involvement. Here, we report a case of small cell lung cancer, which was misdiagnosed as the lymphoma in contrast enhanced CT and Ga-DOTA-NOC PET/CT imagings.

PATIENT CONCERNS

A 49-year-old male with chief complaint of discontinuous cough for 1 month.

DIAGNOSES

Small cell lung cancer.

INTERVENTIONS

Radiotherapy and chemotherapy were given thereafter.

OUTCOMES

The case had multiple enlarged lymph nodes due to tumor progression.

LESSONS

Small cell lung cancer is a malignant and progressive disease, and easy to be ignored in clinical. The case of small cell lung cancer without parenchyma and hilus involvement has never been reported before. Here, we report it and hope it provides a differential diagnosis for clinicians in the following similar cases.

Primary Extranodal Lymphoma of the Thorax

Primary pulmonary lymphomas represent a pathologically heterogeneous group of disorders that often share imaging features, which include peribronchovascular nodules and masses or areas of nonresolving consolidation. Primary mediastinal B-cell lymphoma is an extranodal non-Hodgkin lymphoma seen in younger patients that has imaging and pathologic features that demonstrate some degree of overlap with Hodgkin lymphoma. Primary lymphomas of the pleural space are rare and associated with concomitant viral infections.

Multimodality imaging of cardiothoracic lymphoma

Lymphoma is the most common hematologic malignancy and represents approximately 5.3% of all cancers. The World Health Organization published a revised classification scheme in 2008 that groups lymphomas by cell type and molecular, cytogenetic, and phenotypic characteristics. Most lymphomas affect the thorax at some stage during the course of the disease. Affected structures within the chest may include the lungs, mediastinum, pleura, and chest wall, and lymphomas may originate from these sites as primary malignancies or secondarily involve these structures after arising from other intrathoracic or extrathoracic sources. Pulmonary lymphomas are classified into one of four types: primary pulmonary lymphoma, secondary pulmonary lymphoma, acquired immunodeficiency syndrome-related lymphoma, and post-transplantation lymphoproliferative disorders. Although pulmonary lymphomas may produce a myriad of diverse findings within the lungs, specific individual features or combinations of features can be used, in combination with secondary manifestations of the disease such as involvement of the mediastinum, pleura, and chest wall, to narrow the differential diagnosis. While findings of thoracic lymphoma may be evident on chest radiography, computed tomography has traditionally been the imaging modality used to evaluate the disease and effectively demonstrates the extent of intrathoracic involvement and the presence and extent of extrathoracic spread. However, additional modalities such as magnetic resonance imaging of the thorax and (18)F-FDG PET/CT have emerged in recent years and are complementary to CT in the evaluation of patients with lymphoma. Thoracic MRI is useful in assessing vascular, cardiac, and chest wall involvement, and PET/CT is more accurate in the overall staging of lymphoma than CT and can be used to evaluate treatment response.

Late relapse of testicular seminoma in the posterior mediastinum

Patients with testicular seminoma are usually cured if they survive disease-free for 5 years after therapy. Late relapse can also occur but is rare. In particular, relapse of testicular seminoma in the form of a large mediastinal mass is extremely rare. We present here a 37-year-old man with a late relapse of a large testicular seminoma in the posterior mediastinum, encasing the descending thoracic aorta, and compressing the left atrium and left main bronchus on computed tomography (CT) and positron emission tomography (PET).

An unusual Hodgkin's lymphoma case presenting with upper extremity multiple masses

Almost always, Hodgkin's lymphoma presents with lymph node involvement. Primary extranodal lymphoma is rare and mostly has a type of non-Hodgkin's lymphoma. We present an unusual presentation of a Hodgkin's lymphoma in a 33-year-old man. There were numerous soft tissue masses localized in the subcutaneous tissue of the left arm along the neurovascular bundle and the ipsilateral axillary region. We found only one Hodgkin's lymphoma case that presented as an upper extremity mass reported in the literature. In cases where a great number of successively lined up soft tissue masses are detected on the extremity, lymphoma takes place among the differential diagnoses.

Cross-sectional evaluation of thoracic lymphoma

Thoracic lymphomas most frequently involve mediastinal lymph nodes in the anterior mediastinum and paratracheal areas. The lymphomas may also involve lung, thymus, pleura, pericardium, chest wall, and the breast and their radiologic manifestations are diverse. Lymphomas (mostly BALT lymphoma and large B-cell lymphoma) may arise primarily from the lung with various imaging features including single or multiple nodule(s) and area(s) of consolidation. CT is currently the most important imaging modality for the evaluation of thoracic lymphoma but FDG PET also plays a crucial role in the clinical management of these cases.

Cross-sectional evaluation of thoracic lymphoma

In patients who have lymphoma, the presence and distribution of thoracic involvement is important in both tumor staging and treatment. Thoracic involvement in Hodgkin lymphoma (HL) is more common than in non-Hodgkin lymphoma (NHL). In HL, mediastinal lymphadenopathy with contiguous spread is a hallmark, and lung parenchymal involvement at the initial presentation is almost always associated with mediastinal lymphadenopathy. NHL is more heterogeneous and generally presents at a more advanced stage than HL. Most often, mediastinal involvement occurs as a disseminated or recurrent form of extrathoracic lymphoma. Bulky mediastinal disease with compression of adjacent structures can occur, particularly with high-grade subtypes of NHL and isolated lung disease without mediastinal lymphadenopathy can occur in contrast to HL.

Pneumomediastinum as a complication to treatment of mediastinal (thymic) large B-cell lymphoma

Mediastinal (thymic) large B-cell lymphoma (Med-DLBCL) is a subtype of diffuse large B-cell lymphomas (DLBCL) with a typical radiological appearance of bulky anterior mediastinal mass, often with areas of necrosis. We report a case of Med-DLBCL with unusual radiological findings and clinical development. Computed tomography (CT) obtained at presentation revealed a huge anterior mediastinal tumor with an axial diameter of 180 mm. Nineteen days after the first cycle of chemotherapy, chest radiography and CT revealed large areas of tumor necrosis and pneumomediastinum with air-fluid levels. To our knowledge, air-fluid levels inside Med-DLBCL have not been previously described. This finding, in combination with necrotic sputum, may indicate communication between the tracheobronchial tree and the tumor.

Primary Mediastinal Lymphoma

OBJECTIVE

To assess the characteristic features of the primary mediastinal lymphoma (PML) on CT and to test the relationship between CT findings and the likelihood of the 3 most common subtypes (Hodgkin lymphoma [HL], mediastinal diffuse large B-cell lymphoma [Med-DLBCL], and precursor T-cell lymphoblastic lymphoma [T-LBL]).

METHODS

Sixty-six consecutive patients with pathologically proven PML including 29 patients with HL, 21 with Med-DLBCL, and 16 with T-LBL underwent CT prior to therapy. CT scans were independently reviewed by 2 radiologists who were blinded to the pathologic diagnosis for the following considerations: pattern of involvement (i.e., morphologic features, mass size, and contrast enhancement pattern), and ancillary findings at other sites including neck, abdomen, and pelvis. Interobserver agreement was measured by Kappa statistics, and independent predictors were calculated using multiple logistic regression analysis for determining the likelihood of the subtypes based on CT.

RESULTS

Characteristic features of HL included irregular contour of the anterior mediastinal mass (20 of 29, 69%) and high prevalence of associated mediastinal lymphadenopathy (28 of 29, 97%). Characteristic features of Med-DLBCL included regular contour (14 of 21, 67%) and absence of cervical and abdominal lymphadenopathy (0 of 21). Characteristic features of T-LBL included regular contour (12 of 16, 75%) and high prevalence of cervical (9 of 16, 56%) and abdominal (6 of 16, 38%) lymphadenopathy and splenomegaly (11 of 16, 69%). CT findings independently associated with increased likelihood of HL were surface lobulation (P <0.01), the absence of vascular involvement (P <0.01), or pleural effusion (P <0.05). The presence of vascular involvement was associated with increased likelihood of Med-DLBCL (P <0.001). Furthermore, CT findings including the presence of cervical lymph nodes or inguinal lymph nodes (P <0.001), the presence of pericardial effusion (P <0.05), and the absence of surface lobulation (P <0.05) were significantly associated with the likelihood of T-LBL.

CONCLUSION

The various histologic subtypes of PML have characteristic manifestations in the neck, chest, and abdomen, which allow their distinction on CT.

[Radiological diagnostics of Hodgkin- and non-Hodgkin lymphomas of the thorax]

Malignant lymphomas belong to the most important malignant diseases in western countries with an increasing incidence of Non-Hodgkin lymphoma. The thorax is the location of primary manifestation especially in patients with Hodgkin's disease. Progression of disease and therapy associated complications are frequently located in the chest. Based on morphological imaging criteria the two types of lymphoma cannot be differentiated, helpful for differentiation is, however, the way of disease spread. Primary and secondary thoracic lymphoma represent a diagnostic challenge in radiology: the patterns are variable in radiography as well as in computed tomography and alter under therapy. Radiological studies, especially CT, are an integral part of the staging process. MRI is considered advantageous for chest wall disease. PET as functional imaging technique has its proven role for staging of high grade lymphomas, the combination of functional and morphological information provided by PET-CT will become the first diagnostic standard in the future.

Is chest CT sufficient for follow-up of primary mediastinal B-cell lymphoma in remission?

OBJECTIVE

We aimed to evaluate whether chest CT alone is sufficient for follow-up assessment of patients with primary mediastinal B-cell lymphoma that is in remission.

MATERIALS AND METHODS

A retrospective review of medical records and CT examinations of patients who received a diagnosis of primary mediastinal B-cell lymphoma between January 1989 and January 2000 was performed. The first-year follow-up comprised examinations at 3-month intervals of the neck, chest, abdomen, and pelvis, with the examination modality alternating between CT and gallium scintigraphy. Patients who achieved complete remission underwent the same CT protocol twice the following year and then once a year during sequential follow-up.

RESULTS

Fifty-three patients with primary mediastinal B-cell lymphoma at presentation--31 females and 22 males, ranging in age from 17 to 61 years (average age at diagnosis, 34 years)--were studied. The follow-up time ranged from 6 to 143 months (average follow-up time, 42.4 months). Although 11 of the patients had only a partial remission, 42 patients (79%) achieved complete remission, with one patient lost to follow-up and thus excluded from study. Recurrence was diagnosed in six of these 42 patients. All six had mediastinal recurrence with additional involvement of the lungs, chest wall, pericardium, and pleura. One patient also had bone marrow involvement at recurrence.

CONCLUSION

Recurrence of primary mediastinal B-cell lymphoma in patients who achieve complete remission appears to be confined to the chest. Consequently, chest CT alone is sufficient for routine follow-up of these patients.

Spontaneous extensive necrosis in non-Hodgkin lymphoma: prevalence and clinical significance

PURPOSE

We studied the prevalence of spontaneous extensive necrosis in the nodes of patients with non-Hodgkin lymphomas and assessed the clinical significance of this finding.

METHOD

CT and MRI performed before initiation of radiation or chemotherapy were reviewed in 60 consecutive patients with non-Hodgkin lymphomas to evaluate the presence or absence of spontaneous extensive necrosis in the lymphomatous nodes. The results were correlated with histopathologic grading, stages of lymphomas, maximal axial diameters of the lesions, International Prognostic Index (IPI), age, and serum lactate dehydrogenase (LDH) levels. We then performed Kaplan-Meier analysis of disease-free survival using each factor.

RESULTS

Extensive necrotic nodes that appeared as rim-enhanced masses on enhanced CT or MR images were found in 15 patients (25%), of whom 10 patients had pathologic verification. The patients with necrosis had significantly higher stages (Stage II or higher), greater IPI (IPI of > or = 2), and higher serum LDH levels than those without necrosis (p = 0.001, p = 0.005, and p = 0.005, respectively). With the Kaplan-Meier method, a statistically significant difference was noted for serum LDH levels (p = 0.015) and IPI (p = 0.021) but not for extensive necrosis (p = 0.600).

CONCLUSION

Spontaneous extensive necrosis in lymphomatous nodes is not a rare event. This finding may have a prognostic significance for patients with non-Hodgkin lymphomas.

Primary mediastinal large B-cell lymphoma: the need for prospective controlled clinical trials

Primary mediastinal large-B cell lymphomas (PMLCL) are considered to be a distinct clinicopathologic entity among the diffuse large B-cell lymphomas. This study evaluated the prognostic factors and therapeutic outcome of PMLCL in a single-institution series. Twenty seven patients were reviewed. Nineteen of the 27 had Stage I-II and 8 had Stage III-IV disease. B-symptoms were found in 11 (41%) and bulky disease in 10 (37%) patients. All were initially given combination chemotherapy (CT): doxorubicin-containing regimens to 23 patients (11 patients had CHOP, 12 received more intensive third-generation regimens) and 4 elderly (>70 years) patients received CVP. Eleven responders were consolidated with irradiation (RT) as part of their initial treatment, with a median total dose of 39 Gy. Nineteen patients (70%) achieved clinical remission (15 CR and 4 PR) with their initial therapy. Forty-four percent of patients remained progression-free and 59% are alive at 3 years. The actuarial 10-year time to progression (TTP) and overall survival (OS) were 44% and 50%, respectively. Age >60 years, performance status >1 and IPI intermediate-high to high risk were significantly associated with poorer OS and TTP by univariate analysis (log-rank test). A better outcome was associated with the use of more aggressive chemotherapy regimens or with the inclusion of RT in the first-line treatment. Our analyses suggest that the application of radiotherapy in combination regimens and the use of more aggressive chemotherapy in the treatment of this particular type of lymphoma should now be evaluated in prospective randomized trials.

Primary mediastinal large B-cell lymphoma (PMLCL): the need for prospective controlled clinical trials

Primary mediastinal large-B cell lymphomas (PMLCL) are considered to be a distinct clinicopathologic entity among the diffuse large B-cell lymphomas. This study evaluated the prognostic factors and therapeutic outcome of PMLCL in a single-institution series. Twenty seven patients were reviewed. Nineteen of the 27 had Stage I-II and 8 had Stage III-IV disease. B-symptoms were found in 11 (41%) patients and bulky disease in 10 (37%). All patients were initially given combination chemotherapy (CT): doxorubicin-containing regimens to 23 patients (11 patients had CHOP, 12 more intensive third-generation regimens) and 4 elderly (>70 years) patients received CVP. Eleven responders were consolidated with irradiation (RT) as part of their initial treatment, with a median total dose of 39 Gy. Nineteen patients (70%) achieved clinical remission (15 CR and 4 PR) with their initial therapy. Forty-four percent of patients remained progression-free and 59% are alive at 3 years. The actuarial 10-year TTP and OS were 44% and 50%, respectively. Age >60 years, performance status >1 and IPI intermediate-high to high risk were significantly associated with poorer OS and TTP by univariate analysis (log-rank test). A better outcome was associated with the use of more aggressive chemotherapy regimens or with the inclusion of RT in the first-line treatment. In conclusion our analyses suggest that the application of radiotherapy in combination regimens and the use of more aggressive chemotherapy in the treatment of this particular lymphoma entity should be evaluated in prospective randomized trials.