CONTENTS:

5.11 Pulmonary Lymphoma
5.11.1 Low-Grade, B-Cell Lymphoma
5.11.2 High-Grade, B-Cell Lymphoma
5.11.3 Lymphomatoid Granulomatosis
5.11.4 Pulmonary Langerhans Cell Histiocytosis (Histiocytosis X)

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5.11 Pulmonary Lymphoma

A lymphoma is a clonal or neoplastic proliferation of lymphoid cells. Lymphomas commonly arise in lymphoid tissue, mainly in lymph nodes. Lymphocytes and lymph nodes are present in normal lung so it is not surprising that primary lymphoma can arise in the lung.

Figure 5.8 Primary Pulmonary Lymphoma.

A. Photomicrograph of the histology of low-grade B-cell lymphoma involving
the bronchial epithelium (top). (H&E x20) B. Photomicrograph of the histology
of high-grade B-cell lymphoma. (H&E x60) C. Photomicrograph of the histology
of lymphomatoid granulomatosis shows large, pale lymphocytes mixed with
inflammatory cells. (H&E x40)

5.11.1 Low-Grade B-Cell Lymphoma

Low-grade pulmonary B-cell lymphoma is the most common form of primary pulmonary lymphoma. It originates from mucosa-associated lymphoid tissue, usually seen around bronchi or bronchioles.

Approximately 70 % to 90 % of primary pulmonary lymphomas are low-grade marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT) type. These lymphomas account for less than 0.5% of all primary lung tumors. Patients tend to be in their fifth, sixth or seventh decades, and there is a slight male preponderance. Presentation in younger patients is rare unless they have immune suppression.

Bronchial MALT is the origin of these lymphomas. Bronchial MALT develops as a response to injury or immune stimuli, including smoking.

The histology of pulmonary marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) consists of small B-cells, with scattered immunoblasts, centroblasts, and plasma cell differentiation. The neoplastic cells typically infiltrate the bronchiolar mucosal epithelium, forming ‘lymphoepithelial lesions.’

The following terms for these low-grade lymphomas are now obsolete and include, ‘pseudolymphoma,’ BALT (bronchial associated lymphoid tissue) lymphoma and BALTOMA.

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5.11.2 High-Grade B-Cell Lymphoma

High-grade B-cell lymphoma is a much more rare lymphoma (5% to 10 %) in the lung.  Patients who are diagnosed with this form of lymphoma usually have an underlying immune deficiency or immunological disorder. Patients are usually between 50 to 70 years of age, and there is no sex predisposition.  Primary pulmonary DLBCL may occur as a complication of immune suppression. The etiology is not known, but there is an association collagen vascular diseases, AIDS, and immunodeficiency.

Diffuse large B-cell non-Hodgkin’s lymphoma (DLBCL) has histology that shows a diffuse proliferation of large lymphoid cells, with large, irregular nuclei.

The term ‘high-grade MALT lymphoma’ for these high-grade lymphomas is now obsolete.

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5.11.3 Lymphomatoid Granulomatosis

The inclusion of lymphomatoid granulomatosis as a primary pulmonary lymphoma is controversial. Lymphomatoid granulomatosis (LYG) is an extranodal, angiocentric and angiodestructive lymphoproliferative disorder.

The histology shows a mixed infiltrate of atypical B-lymphocytes that are infected with Epstein-Barr virus (EBV). Lymphomatoid granulomatosis shows a spectrum of  histological grade and clinical aggressiveness.  The grade is related to the proportion of EBV-positive large B cells.  LYG may progress to an EBV-positive, diffuse large B-cell lymphoma.

The prognosis of this condition is extremely variable, with complete remission with steroids and cyclophosphamide for some patients and failure to respond to combination chemotherapy for others.

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5.11.4 Pulmonary Langerhans Cell Histiocytosis (Histiocytosis X)

Pulmonary Langerhans cell histiocytosis  (PLCH) is classified as an ‘interstitial lung disease‘ and is caused by the proliferation of Langerhans cells.  Most affected patients are adults and in most of these patients, the lung is the sole site of involvement.

Synonyms for this condition include ‘histiocytosis X,’ and ‘pulmonary eosinophilic granuloma.’

PLCH is important when considering lung cancer screening diagnoses, as 95% or more of patients are current or former cigarette smokers.

Between 15 % and 20 % of patients are symptomatic.   On imaging, nodules with cystic change are seen in the upper and mid zones of the lungs.  PLCH in adults may rarely be part of a systemic Langerhans cell histiocytosis or Langerhans cell sarcoma.

Figure 5.9 Pulmonary Langerhans Cell Histiocytosis
(Histiocytosis X)

A. Lung CT radiograph shows peripheral lung nodules and cysts.
B. Photomicrograph of the histology from one of these lung nodules
shows pale macrophage-like cells mixed with inflammatory cells,
including variable numbers of eosinophil polymorphs. (H&E x60)

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References:

Cadranel J, Wislez M, Antoine M. (2002). Primary pulmonary lymphoma. Eur Respir J 20, 750–762. (Retrieved 12^th Feb 2015):  https://erj.ersjournals.com/content/20/3/750

Lewis ER, Caskey CI, and Fishman EK. (1991) Lymphoma of the lung: CT findings in 31 patients. American Journal of Roentgenology. 1991;156: 711-714. (Retrieved 12^th Feb 2015): http://www.ajronline.org/doi/abs/10.2214/ajr.156.4.2003430

More references for this section are on this page .

Patient Information:

Lymphoma Association Diffuse large B-cell lymphoma (DLBCL) (Retrieved 24^th April 2015):

MacMillan Cancer Support Malt Lymphoma (Retrieved 23^rd April 2015): http://www.macmillan.org.uk/information-and-support/lymphoma/lymphoma-non-hodgkin/types-of-non-Hodgkin-lymphoma/MALT-lymphoma.html

More patient information for this section is on this page .

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