Primary effusion lymphoma
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Synonyms and keywords: Body cavity lymphoma; PEL

# Overview
Primary effusion lymphoma (PEL) is rare sub-type of diffuse large B-cell lymphoma (DLBCL). Primary effusion lymphoma is a very fast-growing (aggressive) lymphoma usually confined to pleural, pericardial, peritoneal body cavities, presenting as serous effusions without detectable tumor masses. It occurs primarily, but not exclusively, in HIV-infected patients. Lymphoma cells are found in the fluid in these body cavities. Primary effusion lymphoma is associated with human herpes virus 8 (HHV8) infection and Epstein-Barr virus (EBV) infection. On microscopic histopathological analysis, neoplastic proliferation of large lymphoid cells with round to irregular nuclei, prominent nucleoli, and varying amounts of vacuolated cytoplasm are characteristic findings of primary effusion lymphoma. Primary effusion lymphoma is more commonly observed among young or middle-aged patients and males are more commonly affected with PEL than females. Symptoms may include fever, fatigue, weight loss, night sweats, painless swellings in the neck, axilla, groin, thorax, abdomen, chest pain, abdomen pain, bone pain, and skin rash. A lymph node biopsy is generally used in diagnosis of primary effusion lymphoma and the mainstay of therapy for primary effusion lymphoma is chemotherapy and antiretroviral therapy.

# Historical Perspective
- The association between AIDS, Epstein-Barr virus (EBV) and primary effusion lymphoma (PEL) was described in 1989 by DM Knowles and his group.
- In 1995, Cesarman et al was the first scientist to identify the association between KSHV DNA sequences within a distinct sub-type of AIDS and the development of primary effusion lymphoma (PEL).
- Primary effusion lymphoma (PEL) was designated  by Nador et al  that is associated with HHV-8/KSHV, in1996.

# Classification
There is no established system for the classification of primary effusion lymphoma.

# Pathophysiology
- Primary effusion lymphoma is associated with human herpes virus 8  (HHV8) infection and  Epstein-Barr virus (EBV) infection.
- Among a very few of patients with human herpes virus 8 (HHV8) not associated with an effusion (a solid variant of PEL).
- Primary effusion lymphoma most often occurs in immunodeficient patients such as those with HIV/AIDS. It can sometimes occur in people who have had organ transplants.
- On microscopic histopathological analysis, neoplastic proliferation of large lymphoid cells with round to irregular nuclei, prominent nucleoli, and varying amounts of vacuolated cytoplasm are characteristic findings of primary effusion lymphoma.
- There were immunoblastic, plasmablastic and anaplastic variants with bizarre, pleomorphic nuclei.

# Causes
- There are no established causes for primary effusion lymphoma.
- PEL is always associated with HHV-8, also known as Kaposi sarcoma associated herpes.
- PEL is most commonly present in immunodeficient patients, especially those with advanced AIDS.
- An infection with Epstein-Barr virus (EBV) is also present in the majority of primary effusion lymphoma (PEL) cases.

# Differentiating primary effusion lymphoma from other Diseases
- Primary effusion lymphoma must be differentiated from other diseases such as:
- Plasmablastic lymphoma (PBL)
- Burkitt lymphoma
- Pyothorax associated lymphoma (PAL)
- Anaplastic large cell lymphoma (ALCL)
- Diffuse large B-cell lymphoma (DLBCL)

# Epidemiology and Demographics
- Primary effusion lymphoma is usually diagnosed among HIV infection. 
- Primary effusion lymphoma usually has same age and race of HIV patients.
There is no racial predilection to Primary effusion lymphoma.

## Incidence
- The prevalence of primary effusion lymphoma is unknown.
- Primary effusion lymphoma accounts for less than 1% of non-AIDS related lymphomas and 4% of lymphomas associated with AIDS.

## Age
- Primary effusion lymphoma is more commonly observed among young or middle-aged patients.

## Gender
- Males are more commonly affected with primary effusion lymphoma than female (6:1).

# Risk Factors
The most potent risk factor in the development of primary effusion lymphoma is human herpes virus (HHV) infection. Other risk factors include Epstein-Barr virus (EBV) infection, immunodeficient patients, and  HHV-8 infection.
Less common risk factors in the development of  primary effusion lymphoma include:
- Male
Age > 60 years
Systemic disease
Smoking
Radiation and industrial chemicals
Chemotherapy
- Male
- Age > 60 years
- Systemic disease
- Smoking
- Radiation and industrial chemicals
- Chemotherapy

# Screening
There is insufficient evidence to recommend routine screening for primary effusion lymphoma.

# Natural History, Complications, and Prognosis
- Primary effusion lymphoma is a very fast-growing (aggressive) lymphoma.
- They are usually confined to pleural, pericardial, peritoneal cavities, presenting as serous effusions without detectable tumor masses.
- Prognosis is generally poor with average life expectancy of 3-4 months after diagnosis.

# Diagnosis
- Among the patients who present with clinical signs of  PEL usually have HIV infection or Kaposi's sarcoma or Castleman's disease.
- Primary effusion lymphoma diagnosed by pathological analysis of involved tissue .
- WHO describe primary effusion lymphoma (PEL) cells bridge those of large cell immunoblastic lymphoma, cells with basophilic cytoplasm, large round to irregular nuclei, prominent nucleoli.
- CD Markers that found CD45 but not usually lymphocyte markers such as CD19, CD20, CD79a, CD3, CD4, or CD8. 

## Diagnostic Study of Choice
There are no established criteria for the diagnosis of Primary effusion lymphoma.

## Staging
Staging for primary effusion lymphoma is provided in the following table:

## History and Symptoms
- Symptoms of primary effusion lymphoma may include the following:
- Fever
- Fatigue
- Weight loss
- Night sweats
- Painless swellings in the neck, axilla, groin, thorax, and abdomen
- Pain in the chest, abdomen, or bones
- Skin rash

## Physical Examination
- Physical examination of primary effusion lymphoma may be remarkable for:
- Fever
- Skin rash
- Tachypnea
- Cervical lymphadenopathy
- Thoracic masses suggestive of central lymphadenopathy
- Abdominal masses suggestive of central lymphadenopathy
- Peripheral lymphadenopathy
- Lower extremity edema

## Laboratory Findings
- There are no specific laboratory findings associated with primary effusion lymphoma.
- PEL cells typically express a hematolymphoid marker, CD45.
- A lymph node biopsy is diagnostic of primary effusion lymphoma.
- Other laboratory findings consistent with the diagnosis of primary effusion lymphoma include complete blood count, blood chemistry studies, cytogenetic analysis, flow cytometry, immunohistochemistry, and immunophenotyping.

## Electrocardiogram
There are no ECG findings associated with Primary effusion lymphoma.

## X-ray
There are no x-ray findings associated with Primary effusion lymphoma.

## Echocardiography or Ultrasound
There are no echocardiography/ultrasound findings associated with Primary effusion lymphoma.

## CT scan
There are no CT scan findings associated with Primary effusion lymphoma.

## MRI
There are no MRI findings associated with Primary effusion lymphoma.

## Other Imaging Findings
- There are no specific imaging study associated with primary effusion lymphoma.
- CT, MRI, and PET scan may be helpful in the diagnosis of primary effusion lymphoma.

## Other Diagnostic Studies
- Primary effusion lymphoma may also be diagnosed using bone marrow aspiration and biopsy.

# Treatment

## Medical Therapy
- The mainstay of therapy for primary effusion lymphoma is chemotherapy and antiretroviral therapy.
- Drug regimen: CHOP  Cyclophosphamide AND Doxorubicin AND Vincristine AND Prednisone

## Surgery
Surgical intervention is not recommended for the management of primary effusion lymphoma.

## Primary Prevention
There are no established measures for the primary prevention of primary effusion lymphoma.

## Secondary Prevention
There are no established measures for the secondary prevention of primary effusion lymphoma.