Atypical neoplasms 2Dr. Jayanth H Keshavamurthy MD.

Bronchus-associated lymphoid tissue lymphoma

• Primary pulmonary lymphoma is distinguished from the more common secondary pulmonary lymphoma by lack of extrapulmonary involvement.

• BALT lymphoma is the most common type of primary pulmonary lymphoma.

• In a case of chronic multifocal consolidation or multiple pulmonary nodules, BALT lymphoma should be included in the differential diagnosis.

• Bronchus-associated lymphoid tissue (BALT) lymphoma is a rare subtype of primary non-Hodgkin lymphoma that may occur within the lung. 

• BALT lymphoma has variable imaging findings and can mimic other malignancies such as lung adenocarcinoma on CT.

• The most common findings include parenchymal abnormalities such as nodules, masses, consolidation, and ground-glass opacity.

• Intrathoracic (hilar or mediastinal) lymphadenopathy is usually absent. 

• Mucosa-associated lymphoid tissue (MALT) lymphoma is a subtype of non-Hodgkin B-cell lymphoma that can occur anywhere in the body, although it most frequently affects the gastrointestinal system.

• When it presents in the lung, it is called BALT lymphoma. • BALT lymphoma accounts for at least two-thirds of primary pulmonary non-

Hodgkin lymphoma but is overall very uncommon. • The pathogenesis involves long-term antigenic stimulation from autoimmune,

inflammatory, or infectious etiologies. • Associations between BALT lymphoma and smoking, Sjögren disease,

multiple sclerosis, rheumatoid arthritis, diffuse panbronchiolitis, chronic hypersensitivity pneumonitis, and Hashimoto thyroiditis have been proposed. 

• Most cases occur in patients over 50 years of age. Patients usually have no symptoms at presentation, although chest discomfort, cough, breathing difficulty, or hemoptysis may be present. 

• On cross-sectional imaging with CT, BALT lymphoma typically demonstrates nonspecific imaging findings, which include nodules, masses, consolidation, and ground-glass opacity.

• Regions of consolidation may demonstrate indistinct borders and air bronchograms. The lung may be involved in a focal or more diffuse manner. Pleural effusions are uncommon. I

• ntrathoracic (hilar or mediastinal) lymphadenopathy is not a typical feature of BALT. Differential considerations include such entities as lung adenocarcinoma, organizing pneumonia,alveolar sarcoid, multifocal pneumonia and pulmonary metastasis.

• Treatment usually consists of a combination of surgical resection, chemotherapy, radiation therapy, and/or immunotherapy.

• Survival rates are relatively high because the disease is typically diagnosed prior to extrapulmonary extension, and disease progression is slow.

• Lymphangitic carcinomatosis, or lymphangitis carcinomatosa, is the term given to tumour spread through the lymphatics of the lung, and is most commonly seen secondary to adenocarcinoma.

Pathology

• Lymphangitis carcinomatosa is most commonly seen secondary to adenocarcinomas such as:

• breast cancer - most common • lung cancer (bronchogenic adenocarcinoma)• colon cancer• stomach cancer• prostate cancer• cervical cancer• thyroid cancer• It can also be seen in numerous other primary cancers,

e.g. laryngeal cancer,pancreatic cancer, etc. 

Radiographic features

• Radiographic appearances can most easily be divided into those due to involvement of the peripheral (interlobular septae) and central lymphatic system. Involvement may be diffusely of both, or predominantly of one or other compartment . 

• Distribution of changes is variable, but most are asymmetric and patchy .

• It is usually bilateral but may be unilateral especially in cases of lung and breast cancer.

• CT, especially HRCT, is excellent at demonstrating both peripheral and central changes.

• Typically the appearance is that of interlobular septal thickening most often nodular and irregular, although smooth thickening may also sometimes be seen . This results in prominent definition of the secondary pulmonary nodules, manifesting as tessellating polygons. 

• Thickening of the bronchovascular interstitium is usually irregular and nodular, with changes seen extending towards the hilum . 

• The combination may give a characteristic "dot in box" appearance.

• subpleural nodules, and thickening on the interlobar fissures 

• pleural effusion(s): pleural carcinomatosis• hilar and mediastinal nodal enlargement (40-50%)• relatively little destruction of overall lung architecture

Differential diagnosis

• Considerations include a differential for that of thickened interlobular septae, with common entities comprising of :

• sarcoidosis• viral pneumonia• pulmonary oedema - changes are commonly bilateral

and often have a gravitational distribution• radiation pneumonitis• lymphocytic interstitial pneumonitis (LIP)

• KS should be considered in the differential in patients with AIDS who have localized bone pain or a febrile illness of unknown origin.

• Tissue sampling is required to confirm the diagnosis.• Even though the majority of the lesions are lytic they

are usually not seen on plain films. CT or MRI is the preferred imaging modality.

KS is caused by Human Herpesvirus 8. It is a low-grade mesenchymal neoplasm of blood and lymphatic origin primarily affecting the skin. To date, four different types have been described: AIDS-related, African, classic, and transplantation/

immunosuppression. KS usually involves the lungs, gastrointestinal (GI) tract, liver, spleen, and skin. It rarely involves the bone marrow, but there have been multiple biopsy-proven case reports. Bone marrow involvement has been associated

with a poor prognosis.

• On chest plain films, KS usually presents as middle to lower lung zone reticular opacities and parenchymal nodules. On CT, the pulmonary findings are bilateral, symmetric, and poorly marginated nodules arising from the hila. They are characteristically referred to as “flame-shaped” nodules. These nodules tend to coalesce and can grow to measure more than 1 cm and show surrounding ground-glass opacities—this is known as the “halo” sign. Diffuse lymphadenopathy and bilateral pleural effusions are common findings. 

https://3s.acr.org/CIP/SearchCaseView.aspx?CaseId=hATqEbi8jXk%3d

• Pancoast syndrome results from involvement of brachial plexus and sympathetic chain by a Pancoast tumour, or less commonly from other tumours involving the superior pulmonary sulcus.

• The syndrome consists of:• shoulder pain• C8-T2 radicular pain• Horner syndrome• The classical syndrome is uncommon, with the Horner

syndrome present in only 25%.

• Hypertrophic osteoarthropathy is characterised by periosteal reaction without an underlying bone lesion involving the diaphysis and metadiaphysis of the long bones of distal extremities.

• Clubbing of the fingers is seen most commonly in patients with lung, liver, and gastrointestinal disorders.

• When associated with a pulmonary condition it is termed hypertrophic pulmonary osteoarthropathy (HPOA) and when associated with cancer is considered a paraneoplastic syndrome. 

Differential diagnosis

• General imaging differential considerations include:• pachydermoperiostosis• chronic venous insufficiency• thyroid acropachy• hypervitaminosis A

Ganglioneuromas

• Ganglioneuromas are benign tumors of the sympathetic nervous system, most commonly found in the posterior mediastinum

• They are typically homogeneously enhancing round or oval masses which can contain punctate calcifications.

• Ganglioneuromas are tumors of the sympathetic nervous system that originate from neural crest cells. Along with neuroblastomas and ganglioneuroblastomas, ganglioneuromas are collectively known as neurogenic tumors. These three are differentiated only by their stage of neuroblast maturation. Ganglioneuromas are composed of mature ganglion cells and are considered benign tumors. Ganglioneuroblastomas and neuroblastomas are less mature and are considered more aggressive and dangerous.

• The posterior mediastinum is the most frequent site of occurrence (38% of cases), followed by the retroperitoneum. Tumors located in the central nervous system are rare. Ganglioneuromas usually occur in adolescents and young adults (60%) but patients of all ages can be affected. The mean age of occurrence is 7 years.  Patients are usually asymptomatic and these lesions are typically discovered on routine radiographs,

• On imaging, ganglioneuromas are well defined masses which range in appearance from round to lobulated. They show calcifications in 40% of cases and tend to grow around, rather than displace, adjacent blood vessels.

• Tumors with intermediate to high signal intensity on T2 weighted images have a higher degree of cellularity and more collagen, whereas markedly high T2 signal signifies a high myxoid stroma component and low cellularity.

• They also have characteristic curvilinear bands of low intensity on T2 weighted sequences, giving a whorled pattern to the tumor as a result of intertwined schwann cells and collagen fibers.

• Ganglioneuromas homogeneously enhance.

1 r post treatment good response

• IMPRESSION: Extensive sites of extramedullary soft tissue plasmacytomaincluding bilateral lung pleura, bilateral mediastinum includingintensely in the inferior wall right atrium, head of the pancreas,large tumor extending from the posterior wall of the descending colon,lower para-aortic retroperitoneal, 2 mesenteric nodules, largepreaortic tumor beginning at the level of the bifurcation extendinginferiorly midline/left of midline into the lower pelvis supra-vesicleregion, bilateral pelvic sidewalls and periacetabular regions, deepsubcutaneous soft tissue nodule in the right buttock.

• Primary germ cell tumors of the anterior mediastinum are unusual. • Seminomas, embryonal carcinomas, teratocarcinomas, and

choriocarcinomas account for the majority of reported cases . Even less common is a histologically distinctive germ cell tumor called an endodermal sinus tumor or a yolk sac tumor. A recent publication summarized 1 2 reported cases of this tumor primary in the mediastinum (all single case reports).

• Radiologists should include germ cell tumors in their differential diagnosis of anterior mediastinal tumors.

Nodular pleural thickening• Essentially all common causes of nodular pleural thickening are malignant and

include:• metastatic pleural disease, particularly from adenocarcinomas, e.g:

– bronchogenic adenocarcinoma– breast cancer– ovarian cancer– prostate cancer– gastrointestinal adenocarcinoma– renal cell carcinoma

• mesothelioma• lymphoma• invasive thymoma• Thoracic splenosis is a rare benign cause of pleural nodularity.