Small cell lymphoma
Synonyms and keywords: Small cell lymphocytic leukemia; SLL

# Overview
Small cell lymphoma (also known as SLL) is a type of mature B-cell chronic lymphocytic leukemia that presents primarily in the lymph nodes. In 1924, small cell lymphoma was first discovered by the American physician Dr. George Minot. There is no standardized classification system for small cell lymphoma. The pathogenesis of small cell lymphoma is characterized by the malignant infiltration of lymphocytic cells into the bone marrow where they interfere with the production of other hematopoeitic cell lines such as red blood cells and platelets.  Small cell lymphoma arises from pre-follicular center B cells that are normally involved in the process of human immunoglobulins production. Small cell lymphoma represents 90 % of all B-cell chronic lymphocytic leukemias in the United States. Small cell lymphoma presents at a median age of 65 years. Males are slightly more affected with small cell lymphoma than females.  Symptoms of small cell lymphoma may include fever,weight loss, generalized weakness, anorexia, and night sweats. The mainstay therapy of small cell lymphoma is chemotherapy and radiotherapy.

# Historical Perspective
In 1924, small cell lymphoma was first discovered by the American physician Dr. George Minot.

# Classification
There is no classification system for small cell lymphoma. Small cell lymphoma is a subtype of of B-cell chronic lymphocytic leukemia.

# Pathophysiology

## Pathogenesis
- The pathogenesis of small cell lymphoma is characterized by the malignant infiltration of lymphocytic cells into the bone marrow, where they interfere with the production of red blood cells and platelets.
- Small cell lymphoma arises from pre-follicular center B cells that are normally involved in the process of human immunoglobulins production.

## Genetics
Genes involved in the development of small cell lymphoma include:
- Chromosome 11 long arm deletion
- Chromosome 13 long arm deletion (most common genetic mutation)
- Chromosome 17 short arm deletion
- Trisomy 12

## Gross Pathology
There are no remarkable gross pathological findings in small cell lymphoma.

## Microscopic Pathology
On microscopic histopathological analysis, characteristic findings of small cell lymphoma include:
- Small lymphoid cells
- Thin cytoplasmic border
- Dense nucleus
- Lack of nucleolus
- Clumped chromatin aggregates
- The presence of smudge cells
- The presence of gumprecht nuclear shadows
On immunohistopathological analysis, characteristic findings of small cell lymphoma may include:
- CD19
- CD20
- CD23
- CD5

# Causes
There are no established causes for small cell lymphoma.

# Differentiating Small Cell Lymphoma from Other Diseases
Small cell lymphoma must be differentiated from other diseases that cause fever, anorexia, and weakness such as:
- Anemia
- Plasma cell neoplasm
- Hairy cell leukemia
- Mantle cell lymphoma

# Epidemiology and Demographics

## Prevalence
The prevalence of small cell lymphoma is low. Small cell lymphoma represents 90 % of all B-cell chronic lymphocytic leukemias in the United States.

## Age
The median age at diagnosis is 65 years.

## Gender
Males are more commonly affected with small cell lymphoma than females.

## Race
There is no racial predilection for small cell lymphoma.

# Risk Factors
The risk factors for the development of small cell lymphoma are not well established. The most consistent risk factor is a family history of non-hodgkins lymphoma.

# Natural History, Complications and Prognosis

## Natural History
The majority of patients with small cell lymphoma are symptomatic. Early clinical features include generalized weakness, anorexia, and night sweats. If left untreated, patients with small cell lymphoma may progress to develop recurrent infections.

## Complications
Common complications of small cell lymphoma include:
- Severe immunodeficiency
- Warm autoimmune hemolytic anemia
- Richter's transformation

## Prognosis
The prognosis of small cell lymphoma is generally poor; the 5-year survival rate of patients with small cell lymphoma is approximately 51-67%.

# Diagnosis

## Symptoms
Symptoms of small cell lymphoma may include the following:
- Fever
- Weight loss
- Muscle wasting
- Generalized weakness
- Anorexia
- Night sweats

## Physical Examination
Patients with small cell lymphoma often appear pale and malnourished. Physical examination may be remarkable for:
- Pallor
- Petechiae
- Leukemia cutis (infiltration of neoplastic leukocytes or their precursors into the skin resulting in clinically identifiable cutaneous lesions)
- Enlarged and palpable cervical lymph nodes
- Dacryoadenitis

## Laboratory Findings
Laboratory findings consistent with the diagnosis of small cell lymphoma include:
- Absolute lymphocytosis (>5000 cells/l)
- Decreased hemoglobin concentration
- Decreased platelets count

## Imaging Findings
There are no specific imaging findings associated with small cell lymphoma. CT scan may be helpful in the diagnosis small cell lymphoma, findings may include enlarged lymph nodes (>2 cm).

# Treatment

## Medical Therapy
The mainstay of therapy for small cell lymphoma is chemotherapy and radiotherapy.

## Surgery
Surgery is not recommended among patients with small cell lymphoma.
- The diagnosis of small cell lymphoma is made with a excisional lymph node biopsy combined with a bone marrow biopsy.

## Prevention

### Primary Prevention
There are no primary preventive measures available for small cell lymphoma.

### Secondary Prevention
Secondary prevention strategies following small cell lymphoma include follow up every 6 to 12 months. Follow-up testing includes a complete blood count and physical examination.