Second most common primary anterior mediastinal mass in adults. Most are seen in the anterior compartment and rest are seen in middle compartment. Hodgkin's usually present in 40-50's with nodular sclerosing type (7), and non-Hodgkin's in all age groups. Can also be primary mediastinal B-cell lymphoma with exceptionally good prognosis. Common symptoms include fever, weight loss, night sweats, and compressive symptoms such as pain, dyspnea, wheezing, Superior vena cava syndrome, pleural effusions (10,11). Diagnosis usually by CT showing lobulated mass. Confirmation done by tissue biopsy of accompanying nodes if any, mediastinoscopy, mediastinotomy, or thoracotomy. FNA biopsy is usually not adequate. (12,13,14) Treatment of mediastinal Hodgkin's involves chemotherapy and/or radiation. 5 year survival is now around 75%. (15) Large-cell type may have somewhat better prognosis. Surgery is generally not performed because of invasive nature of tumor.

Of all cancers involving the same class of blood cell, 2% of cases are mediastinal large B cell lymphomas.

Biopsy of affected lymph nodes or organs confirms the diagnosis, although a needle aspiration of an affected lymph node can increase suspicion of the disease. X-rays, ultrasound and bone marrow biopsy reveal other locations of the cancer. There are now a range of blood tests that can be utilised to aid in the diagnosis of lymphoma. Flow cytometry detects antibodies linked to tumour cell surface antigens in fluid samples or cell suspensions. Polymerase chain reaction (PCR) for antigen receptor rearrangements (PARR) identifies circulating tumour cells based on unique genetic sequences. The canine Lymphoma Blood Test (cLBT) measures multiple circulating biomarkers and utilises a complex algorithm to diagnose lymphoma. This test utilises the acute phase proteins (C-Reactive Protein and Haptoglobin). In combination with basic clinical symptoms, it gives in differential diagnosis the sensitivity 83.5% and specificity 77%. The TK canine cancer panel is an indicator of general neoplastic disease. The stage of the disease is important to treatment and prognosis. Certain blood tests have also been shown to be prognostic.

The stage of the disease is important to treatment and prognosis.

- Stage I - only one lymph node or lymphoid tissue in one organ involved.

- Stage II - lymph nodes in only one area of the body involved.

- Stage III - generalized lymph node involvement.

- Stage IV - any of the above with liver or spleen involvement.

- Stage V - any of the above with blood or bone marrow involvement.

Each stage is divided into either "substage a", those without systemic symptoms; or "substage b", those with systemic symptoms such as fever, loss of appetite, weight loss, and fatigue.

The factors of poor prognosis for patients with thyroid lymphoma are advanced stage of the tumor, large size (>10 cm) as well as spreading to mediastinum. The overall survival for primary thyroid lymphoma is 50% to 70%, ranging from 80% in stage IE to less than 36% in stage IIE and IVE in 5 years.

PEL is unusual in that the majority of cases arise in body cavities, such as the pleural space or the pericardium; another name for PEL is "body cavity lymphoma".

The immunophenotype : CD45+ (95%), CD20-, CD79a-, PAX5-, CD30+, CD38+, CD138+ and EMA+. Staining the nucleus for HHV-8 LANA may be helpful.

Most common primary anterior mediastinal tumor (20%) in adults but rarely seen in children. It can be classified as lymphocytic, epithelial, or spindle cell histologies, but the clinical significance of these classifications is controversial. Tonofibrils seen under electron microscopy can differentiate thymoma from other tumors such as carcinoid, Hodgkin's, and seminoma. Patients are usually asymptomatic but can present with myasthenia gravis-related symptoms, substernal pain, dyspnea, or cough. Invasive tumors can produce compression effects such as superior vena cava syndrome. (3,4) Thymomas are diagnosed with CT or MRI revealing a mass in anterior mediastinum. Therapy in stage I tumors consists of surgical resection with good prognosis. Stage II-III requires maximal resection possible followed by radiation. Stage IV disease requires addition of cisplatin-based chemotherapy in addition to those in stage II and III. For those with invasive thymoma, treatment is based on induction chemotherapy, surgical resection, and post-surgical radiation. 5-year survival for invasive thymoma is between 12-54% regardless of any myasthenia gravis symptoms (5,6).

It is generally resistant to cancer chemotherapy drugs that are active against other lymphomas, and carries a poor prognosis.

Sirolimus has been proposed as a treatment option.

In order to diagnose MALT, a biopsy is needed from the affected tissue. If the abnormal tissue is suspected to be in the stomach or bowel, an endoscopy is done in order to get the biopsy. This requires either a gastroscopy or colonoscopy. If the lymphoma is thought to have spread to other areas in this region, an ultrasound scan is often done at the same time. If the abnormal tissue is thought to be in the lungs, a bronchoscopy is ordered.

In order to determine the correct type of lymphoma and stage it accurately, the physician will also need to do a physical exam, blood tests to determine blood cell counts, a CT scan, an MRI and/or a PET scan. A PET scan is the most important in planning a course of treatment.

A bone marrow biopsy may be ordered to test for lymph node involvement. If the lymphoma is in the stomach, the physician will test for H.pylori infection through a stool sample. This infection would be necessary to treat in conjunction to treating the cancer.

The prognosis varies according with the type of ALCL. During treatment, relapses may occur but these typically remain sensitive to chemotherapy.

Those with ALK positivity have better prognosis than ALK negative ALCL. It has been suggested that ALK-negative anaplastic large-cell lymphomas derive from other T-cell lymphomas that are morphologic mimics of ALCL in a final common pathway of disease progression. Whereas ALK-positive ALCLs are molecularly characterized and can be readily diagnosed, specific immunophenotypic or genetic features to define ALK-negative ALCL are missing and their distinction from other T-cell non-Hodgkin lymphomas (T-NHLs) remains controversial, although promising diagnostic tools for their recognition have been developed and might be helpful to drive appropriate therapeutic protocols.

Systemic ALK+ ALCL 5-year survival: 70–80%.

Systemic ALK- ALCL 5-year survival: 15–45%.

Primary Cutaneous ALCL: Prognosis is good if there is not extensive involvement regardless of whether or not ALK is positive with an approximately 90% 5-year survival rate.

Breast implant-associated ALCL has an excellent prognosis when the lymphoma is confined to the fluid or to the capsule surrounding the breast implant. This tumor can be recurrent and grow as a mass around the implant capsule or can extend to regional lymph nodes if not properly treated.

Thyroid lymphoma shows a diagnostic and therapeutic challenge in many cases, because some manifestation patterns are similar to anaplastic thyroid cancer (ATC). Performance of fine-needle aspiration (FNA) has helped to distinguish these between two entities preoperatively.

Diagnosis usually occurs at an early stage of disease progression.

Prognoses and treatments are different for HL and between all the different forms of NHL, and also depend on the grade of tumour, referring to how quickly a cancer replicates. Paradoxically, high-grade lymphomas are more readily treated and have better prognoses: Burkitt lymphoma, for example, is a high-grade tumour known to double within days, and is highly responsive to treatment. Lymphomas may be curable if detected in early stages with modern treatment.

Splenic MZL is difficult to diagnose and can look similar to other types of lymphoma. Tests include a physical examination, blood tests to determine overall health and detect infections (ex. hepatitis C), a bone marrow biopsy, CT scan, and a PET scan. Sometimes a splenectomy is necessary during the diagnosis process in order to determine the exact type of lymphoma. If the spleen is removed, you will be at a larger risk of infection.

The majority of gastric lymphomas are non-Hodgkin's lymphoma of B-cell origin. These tumors may range from well-differentiated, superficial involvements (MALT) to high-grade, large-cell lymphomas. Sometimes, it's hard to differentiate poorly differentiated high grade B-cell gastric lymphoma from gastric adenocarcinoma clinically or radiologically, yet histopathology with immunohistochemistry is recommended to stain specific markers on the malignant cell that favor the diagnosis of lymphoma. Immunohistochemistry stains specific clusters of differentiation that are present on B-cells like CD20. Cytokeratin is also a surface marker that is presented on epithelial cells, is stained histochemically and favors the diagnosis of epithelial tumors like adenocarcinoma.

Differentiating poor gastric lymphoma from adenocarcinoma is essential because the prognosis and modalities of treatment differ significantly.

Other lymphomas involving the stomach include mantle cell lymphoma and T-cell lymphomas which may be associated with enteropathy; the latter usually occur in the small bowel but have been reported in the stomach.

Gastric MALT lymphoma is frequently associated (72–98%) with chronic inflammation as a result of the presence of "Helicobacter pylori", potentially involving chronic inflammation, or the action of "H. pylori" virulence factors such as CagA.

The initial diagnosis is made by biopsy of suspicious lesions on esophagogastroduodenoscopy (EGD, upper endoscopy). Simultaneous tests for "H. pylori" are also done to detect the presence of this microbe.

In other sites, chronic immune stimulation is also suspected in the pathogenesis (e.g. association between chronic autoimmune diseases such as Sjögren's syndrome and Hashimoto's thyroiditis, and MALT lymphoma of the salivary gland and the thyroid).

Tumors generally located in the peripheral lymph nodes which can be detected via PET scan and CT scan.

As the appearance of the hallmark cells, pattern of growth (nesting within lymph nodes) and positivity for EMA may mimic metastatic carcinoma, it is important to include markers for cytokeratin in any diagnostic panel (these will be negative in the case of anaplastic lymphoma). Other mimics include CD30 positive B-cell lymphomas with anaplastic cells (including Hodgkin lymphomas). These are identified by their positivity for markers of B-cell lineage and frequent presence of markers of EBV. Primary cutaneous T-cell lymphomas may also be positive for CD30; these are excluded by their anatomic distribution. ALK positivity may also be seen in some large-cell B-cell lymphomas and occasionally in rhabdomyosarcomas.

After a diagnosis and before treatment, a cancer is staged. This refers to determining if the cancer has spread, and if so, whether locally or to distant sites. Staging is reported as a grade between I (confined) and IV (spread). Staging is carried out because the stage of a cancer impacts its prognosis and treatment.

The Ann Arbor staging system is routinely used for staging of both HL and NHL. In this staging system, I represents a localized disease contained within a lymph node, II represents the presence of lymphoma in two or more lymph nodes, III represents spread of the lymphoma to both sides of the diaphragm, and IV indicates tissue outside a lymph node.

CT scan or PET scan imaging modalities are used to stage a cancer.

Age and poor performance status are established poor prognostic factors, as well.

These lymphomas are difficult to differentiate from gastric adenocarcinoma. The lesions are usually ulcers with a ragged, thickened mucosal pattern on contrast radiographs.

The diagnosis is typically made by biopsy at the time of endoscopy. Several endoscopic findings have been reported, including solitary ulcers, thickened gastric folds, mass lesions and nodules. As there may be infiltration of the submucosa, larger biopsy forceps, endoscopic ultrasound guided biopsy, endoscopic submucosal resection, or laparotomy may be required to obtain tissue.

Imaging investigations including CT scans or endoscopic ultrasound are useful to stage disease. Hematological parameters are usually checked to assist with staging and to exclude concomitant leukemia. An elevated LDH level may be suggestive of lymphoma.

Due to the causal relationship between "H. pylori" infection and MALT lymphoma, identification of the infection is mandatory. Histological examination of GI biopsies yields a sensitivity of 95% with five biopsies, but these should be from sites uninvolved by lymphoma and the identification of the organism may be compromised by areas of extensive intestinal metaplasia. As proton-pump inhibition can suppress infection, any treatment with this class of drug should be ceased 2 weeks prior to biopsy retrieval. Serology should be performed if histology is negative, to detect suppressed or recently treated infections. Following the recognition of the association of gastric MALT lymphoma with "H. pylori" infection, it was established that early-stage gastric disease could be cured by "H. pylori" eradication, which is now the mainstay of therapy. Fifty to 95% of cases achieve complete response (CR) with "H. pylori" treatment.

A t(11;18)(q21;q21) chromosomal translocation, giving rise to an "API2-MLT" fusion gene, is predictive of poor response to eradication therapy.

Hodgkin's lymphoma must be distinguished from non-cancerous causes of lymph node swelling (such as various infections) and from other types of cancer. Definitive diagnosis is by lymph node biopsy (usually excisional biopsy with microscopic examination). Blood tests are also performed to assess function of major organs and to assess safety for chemotherapy. Positron emission tomography (PET) is used to detect small deposits that do not show on CT scanning. PET scans are also useful in functional imaging (by using a radiolabeled glucose to image tissues of high metabolism). In some cases a Gallium scan may be used instead of a PET scan.

Radiotherapy is the most effective treatment for local disease either as the sole treatment for low-grade lymphoma or in combination with chemotherapy for intermediate- and high-grade lymphoma. Radiotherapy dose in range of 30-45 Gy administered in fractions are advised in treating the local orbital lymphomas.

Diagnosis generally requires stained slides of a surgically removed part of a lymph node. Other methods are also commonly used, including cytogenetics and fluorescence in situ hybridization (FISH). Polymerase chain reaction (PCR) and CER3 clonotypic primers are additional methods, but are less often used.

The immunophenotype profile consists of CD5+ (in about 80%), CD10-/+, and it is usually CD5+ and CD10-. CD20+, CD23-/+ (though plus in rare cases). Generally, cyclin D1 is expressed but it may not be required. The workup for Mantle cell lymphoma is similar to the workup for many indolent lymphomas and certain aggressive lymphomas.

Mantle cell lymphoma is a systemic disease with frequent involvement of the bone marrow and gastrointestinal tract (generally showing polyposis in the lining). There is also a not-uncommon leukemic phase, marked by presence in the blood. For this reason, both the peripheral blood and bone marrow are evaluated for the presence of malignant cells. Chest, abdominal, and pelvic CT scans are routinely performed.

Since mantle cell lymphoma may present a lymphomatous polyposis coli and colon involvement is common, colonoscopy is now considered a routine part of the evaluation. Upper endoscopy and neck CT scan may be helpful in selected cases. In some patients with the blastic variant, lumbar puncture is done to evaluate the spinal fluid for involvement.

CT scan - Computerized tomography scan yields images of part or whole body. Gives a large number of slices on X-ray image.

PET scan - Generally of the whole body, shows a three-dimensional image of where previously injected radioactive glucose is metabolized at a rapid rate. Faster-than-average metabolism indicates that cancer is likely present. Metabolism of radioactive glucose may give a false positive, particularly if the patient has exercised before the test.

PET scans are much more effective when the information from them is integrated with that from a CT scan to show more precisely where the cancer activity is located and to more accurately measure the size of tumors.

The staging is the same for both Hodgkin's and non-Hodgkin's lymphomas.

After Hodgkin lymphoma is diagnosed, a patient will be "staged": that is, they will undergo a series of tests and procedures that will determine what areas of the body are affected. These procedures may include documentation of their histology, a physical examination, blood tests, chest X-ray radiographs, computed tomography (CT)/Positron emission tomography (PET)/magnetic resonance imaging (MRI) scans of the chest, abdomen and pelvis, and usually a bone marrow biopsy. Positron emission tomography (PET) scan is now used instead of the gallium scan for staging. On the PET scan, sites involved with lymphoma light up very brightly enabling accurate and reproducible imaging. In the past, a lymphangiogram or surgical laparotomy (which involves opening the abdominal cavity and visually inspecting for tumors) were performed. Lymphangiograms or laparotomies are very rarely performed, having been supplanted by improvements in imaging with the CT scan and PET scan.

On the basis of this staging, the patient will be classified according to a staging classification (the Ann Arbor staging classification scheme is a common one):

- Stage I is involvement of a single lymph node region (I) (mostly the cervical region) or single extralymphatic site (Ie);

- Stage II is involvement of two or more lymph node regions on the same side of the diaphragm (II) or of one lymph node region and a contiguous extralymphatic site (IIe);

- Stage III is involvement of lymph node regions on both sides of the diaphragm, which may include the spleen (IIIs) or limited contiguous extralymphatic organ or site (IIIe, IIIes);

- Stage IV is disseminated involvement of one or more extralymphatic organs.

The absence of systemic symptoms is signified by adding "A" to the stage; the presence of systemic symptoms is signified by adding "B" to the stage. For localised extranodal extension from mass of nodes that does not advance the stage, subscript "E" is added. Splenic involvement is signified by adding "S" to the stage. The inclusion of "bulky disease" is signified by "X".

Due to the high risk of recurrence and ensuing problems, close monitoring of dogs undergoing chemotherapy is important. The same is true for dogs that have entered remission and ceased treatment. Monitoring for disease and remission/recurrence is usually performed by palpation of peripheral lymph nodes. This procedure detects gross changes in peripheral lymph nodes. Some of the blood tests used in diagnosing lymphoma also offer greater objectivity and provide an earlier warning of an animal coming out of remission.

Complete cure is rare with lymphoma and treatment tends to be palliative, but long remission times are possible with chemotherapy. With effective protocols, average first remission times are 6 to 8 months. Second remissions are shorter and harder to accomplish. Average survival is 9 to 12 months. The most common treatment is a combination of cyclophosphamide, vincristine, prednisone, L-asparaginase, and doxorubicin. Other chemotherapy drugs such as chlorambucil, lomustine (CCNU), cytosine arabinoside, and mitoxantrone are sometimes used in the treatment of lymphoma by themselves or in substitution for other drugs. In most cases, appropriate treatment protocols cause few side effects, but white blood cell counts must be monitored.

Allogeneic and autologous stem cell transplantations (as is commonly done in humans) have recently been shown to be a possible treatment option for dogs. Most of the basic research on transplantation biology was generated in dogs. Current cure rates using stem cell therapy in dogs approximates that achieved in humans, 40-50%.

When cost is a factor, prednisone used alone can improve the symptoms dramatically, but it does not significantly affect the survival rate. The average survival times of dogs treated with prednisone and untreated dogs are both one to two months. Using prednisone alone can cause the cancer to become resistant to other chemotherapy agents, so it should only be used if more aggressive treatment is not an option.

Isotretinoin can be used to treat cutaneous lymphoma.

According to the WHO criteria, the disease is morphologically graded into:

- grade 1 (<5 centroblasts per high-power field (hpf))

- grade 2 (6–15 centroblasts/hpf)

- grade 3 (>15 centroblasts/hpf).

Grade 3 is further subdivided into:

- grade 3A (centrocytes still present)

- grade 3B (the follicles consist almost entirely of centroblasts)

The WHO 2008 update classifies grades 1 and 2 now as low grade follicular lymphoma, grade 3A as high grade follicular lymphoma, and grade 3B as Diffuse Large B Cell Lymphoma (DLBCL).