Sandbox: Langerhans: Difference between revisions
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==Overview== | ==Overview== | ||
==Pathogenesis== | ==Pathogenesis== | ||
==Genetics== | ==Genetics== | ||
==Associated Conditions== | ==Associated Conditions== | ||
==Gross Pathology== | ==Gross Pathology== | ||
==Microscopic Pathology== | ==Microscopic Pathology== | ||
There are ongoing investigations to determine whether Langerhans cell histiocytosis is a reactive (non-cancerous) or neoplastic (cancerous) process. | |||
Arguments supporting the reactive nature of Langerhans cell histiocytosis include the occurrence of spontaneous remissions, the extensive secretion of multiple cytokines by dendritic cells and bystander-cells (a phenomenon known as cytokine storm) in the lesional tissue, favorable prognosis, and relatively good survival rate in patients without organ dysfunction.[14][15] | |||
On the other hand, the infiltration of organs by monoclonal population of pathologic cells, and the successful treatment of subset of disseminated disease using chemotherapeutic regimens are all consistent with a neoplastic process.[16][17][18] | |||
In addition, a demonstration, using X chromosome–linked DNA probes, of LCH as a monoclonal proliferation provided additional support for the neoplastic origin of this disease.[19] | |||
While clonality is an important attribute of cancer, its presence does not prove that a proliferative process is neoplastic. | |||
Recurrent cytogenetic or genomic abnormalities would also be required to demonstrate convincingly that LCH is a malignancy. | |||
Activating mutation of a protooncogen in the Raf family, the BRAF gene, was detected in 35 of 61 (57%) LCH biopsy samples with mutations being more common in patients younger than 10 years (76%) than in patients aged 10 years and older (44%).[20] This study documented the first recurrent mutation in LCH samples. Two independent studies have confirmed this finding.[21][22] Presence of this activating mutation could support the notion to characterize LCH as myeloproliferative disorder. | |||
Revision as of 15:11, 2 February 2016
Overview
Pathogenesis
Genetics
Associated Conditions
Gross Pathology
Microscopic Pathology
There are ongoing investigations to determine whether Langerhans cell histiocytosis is a reactive (non-cancerous) or neoplastic (cancerous) process. Arguments supporting the reactive nature of Langerhans cell histiocytosis include the occurrence of spontaneous remissions, the extensive secretion of multiple cytokines by dendritic cells and bystander-cells (a phenomenon known as cytokine storm) in the lesional tissue, favorable prognosis, and relatively good survival rate in patients without organ dysfunction.[14][15]
On the other hand, the infiltration of organs by monoclonal population of pathologic cells, and the successful treatment of subset of disseminated disease using chemotherapeutic regimens are all consistent with a neoplastic process.[16][17][18]
In addition, a demonstration, using X chromosome–linked DNA probes, of LCH as a monoclonal proliferation provided additional support for the neoplastic origin of this disease.[19] While clonality is an important attribute of cancer, its presence does not prove that a proliferative process is neoplastic. Recurrent cytogenetic or genomic abnormalities would also be required to demonstrate convincingly that LCH is a malignancy.
Activating mutation of a protooncogen in the Raf family, the BRAF gene, was detected in 35 of 61 (57%) LCH biopsy samples with mutations being more common in patients younger than 10 years (76%) than in patients aged 10 years and older (44%).[20] This study documented the first recurrent mutation in LCH samples. Two independent studies have confirmed this finding.[21][22] Presence of this activating mutation could support the notion to characterize LCH as myeloproliferative disorder.