Hepatosplenic T cell lymphoma overview

# Overview
Hepatosplenic T cell lymphoma arises from an immature cytotoxic T-cell clonally expressing the  T-cell receptor. Gamma delta () T cells constitute 1% to 5% of the circulating lymphocytes in human blood. These cells preferentially home in on some epithelial rich tissues and sinusoidal areas of the splenic red pulp where they represent up to 30% of the whole T-cell population. Hepatosplenic  T-cell lymphoma (HSTCL) is a rare aggressive subtype of extra nodal lymphoma. Genes involved in the pathogenesis of hepatosplenic T cell lymphoma include isochromosome 7q, TRG, and T-cell receptor (TCR) Gamma/Delta genes. On gross pathology, Diffuse enlargment of liver and spleen are characteristic findings of hepatosplenic T cell lymphoma. On microscopic histopathological analysis, monotonous appearance, small amount of cytoplasm, and inconspicuous nucleoli are characteristic findings of neoplastic cells of hepatosplenic T cell lymphoma. There are no established causes for hepatosplenic T cell lymphoma. Hepatosplenic T cell lymphoma is a common disease that tends to affect young adults and adolescents. Males are more commonly affected with hepatosplenic T cell lymphoma than females. There are no established risk factors for hepatosplenic T cell lymphoma. According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for hepatosplenic T cell lymphoma. Hepatosplenic T cell lymphoma must be differentiated from other diseases such as splenic marginal zone lymphoma, cutaneous T cell lymphoma, extranodal NK-T-cell lymphoma, and angioimmunoblastic T-cell lymphoma. Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as poor. According to the Lugano classification, there are four stages of hepatosplenic T cell lymphoma based on the number of nodes and extranodal involvement. The most common symptoms of hepatosplenic T cell lymphoma include fever, fatigue, weight loss, skin rash, night sweats, skin rash, chest pain, abdominal pain, bone pain, and painless swelling in the neck, axilla, groin, thorax, and abdomen. Common physical examination findings of hepatosplenic T cell lymphoma include fever, rash, ulcer, parlor, chest tenderness, abdomen tenderness, hepatomegaly, splenomegaly, bone tenderness, peripheral lymphadenopathy, and central lymphadenopathy. Laboratory tests for hepatosplenic T cell lymphoma include complete blood count (CBC), blood chemistry studies, cytogenetic analysis, flow cytometry, immunohistochemistry,  and immunophenotyping.CT scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma.MRI scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma. On abdominal ultrasound, hepatosplenic T cell lymphoma is characterized by hepatomegaly and splenomegaly. PET scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma. Other diagnostic studies for hepatosplenic T cell lymphoma include laparoscopy, laparotomy, bone marrow aspiration, and bone marrow biopsy. The predominant therapy for hepatosplenic T cell lymphoma is chemotherapy. Adjunctive stem cell transplant may be required.

# Pathophysiology
Hepatosplenic T cell lymphoma arises from an immature cytotoxic T-cell clonally expressing the  T-cell receptor. Gamma delta () T cells constitute 1% to 5% of the circulating lymphocytes in human blood. These cells preferentially home in on some epithelial rich tissues and sinusoidal areas of the splenic red pulp where they represent up to 30% of the whole T-cell population. Hepatosplenic  T-cell lymphoma (HSTCL) is a rare aggressive subtype of extra nodal lymphoma. Genes involved in the pathogenesis of hepatosplenic T cell lymphoma include isochromosome 7q, TRG@, and T-cell receptor (TCR) Gamma/Delta genes. On gross pathology, Diffuse enlargment of liver and spleen are characteristic findings of hepatosplenic T cell lymphoma. On microscopic histopathological analysis, monotonous appearance, small amount of cytoplasm, and inconspicuous nucleoli are characteristic findings of neoplastic cells of hepatosplenic T cell lymphoma.

# Causes
There are no established causes for hepatosplenic T cell lymphoma.

# Epidemiology and Demographics
Hepatosplenic T cell lymphoma is a common disease that tends to affect young adults and adolescents. Males are more commonly affected with hepatosplenic T cell lymphoma than females.

# Risk Factors
There are no established risk factors for hepatosplenic T cell lymphoma.

# Screening
According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for hepatosplenic T cell lymphoma.

# Differential Diagnosis
Hepatosplenic T cell lymphoma must be differentiated from other diseases such as splenic marginal zone lymphoma, cutaneous T cell lymphoma, extranodal NK-T-cell lymphoma, and angioimmunoblastic T-cell lymphoma.

# Prognosis
Depending on the extent of the tumor at the time of diagnosis, the prognosis may vary. However, the prognosis is generally regarded as poor.

# Diagnosis

## Staging
According to the Lugano classification, there are four stages of hepatosplenic T cell lymphoma based on the number of nodes and extranodal involvement.

## Symptoms
The most common symptoms of hepatosplenic T cell lymphoma include fever, fatigue, weight loss, skin rash, night sweats, chest pain, abdominal pain, bone pain, and painless swelling in the neck, axilla, groin, thorax, and abdomen.

## Physical Examination
Common physical examination findings of hepatosplenic T cell lymphoma include fever, rash, ulcer, pallor, chest tenderness, abdominal tenderness, hepatomegaly, splenomegaly, bone tenderness, peripheral lymphadenopathy, and central lymphadenopathy.

## Laboratory tests
Laboratory tests for hepatosplenic T cell lymphoma include complete blood count (CBC), blood chemistry studies, cytogenetic analysis, flow cytometry, immunohistochemistry,  and immunophenotyping.

## Biopsy
Lymph node or extra nodal tissue (liver, spleen, and bone marrow) biopsy is diagnostic of hepatosplenic T cell lymphoma.

## CT
CT scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma.

## MRI
MRI scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma.

## Ultrasound
On abdominal ultrasound, hepatosplenic T cell lymphoma is characterized by hepatomegaly and splenomegaly.

## Other imaging findings
PET scan may be helpful in the diagnosis of hepatosplenic T cell lymphoma.

## Other Diagnostic Studies
Other diagnostic studies for hepatosplenic T cell lymphoma include laparoscopy, laparotomy, bone marrow aspiration, and bone marrow biopsy.

# Treatment

## Medical Therapy
The predominant therapy for hepatosplenic T cell lymphoma is chemotherapy. Adjunctive stem cell transplant may be required.