Histiocytosis Flashcards
Which cells are abnormally activated in histiocytic disorders?
The histiocytoses are a heterogenous group of disorders characterized by abnormal proliferation, activation, and cytokine release by cells involved in phagocytosis and antigen presentation, such as dendritic cells, monocytes, macrophages, and histiocytes.
What is the median age for LCH to occur?
2.5 years of age
Which is the most common of the histiocytoses?
Langerhans cell histiocytosis
What are the most common early signs of LCH?
Gingival hypertrophy and oral ulcers.
What are the most frequent presenting signs in LCH?
Skin rash in the diaper area or scalp, or lytic bone lesions, most commonly in the skull, that are often painful.
What are some common secondary symtpoms found in patients with LCH?
Fever, weight loss, diarrhea, diabetes insipidus (from pituitary involvement), and a history of draining otitis.
Which endocrine disease can be seen with LCH involving the pituitary gland?
Diabetes insipidus
Which organ systems are high-risk in LCH?
Liver, spleen, lungs, and bone marrow.
Which organ systems are low-risk in LCH?
Skin, bones, lymph nodes, and the pituitary gland.
What are the characteristic findings on skin biopsy in patients with LCH?
A large number of pathologic Langerhans cells, along with lymphocytes, macrophages, granulocytes, eosinophils, and multinucleated giant cells.
What immunohistochemistry findings are diagnostic for Langerhans Cell Histiocytosis?
CD1a or CD207 (langerin)
What is the characteristing finding on electron microscopy for patients with LCH?
Birbeck granules. *** Picture?
What is the prognosis in low-risk vs high-risk patients diagnosed with Langerhans Cell Histiocytosis?
Low-risk patients have cure rates >90%. High-risk patients can have mortality approaching 50%.
Distinguish between primary and secondary HLH.
Primary HLH is a rare autosomal recessive disorder that usually occurs before one year of age. Secondary HLH occurs later, with EBV and other infections acting as a trigger.
In what clinical scenario should HLH be suspected?
Suspect HLH in children with cytopenias and hepatosplenomegaly.
What laboratory findings would you expect in a patient with HLH?
Pancytopenia, hyperferritinemia, hypertriglyceridemia, and hypofibrogenemia.
What are the diagnostic criteria for HLH?
Diagnosis requires that at least five of the following criteria be met: Fever, splenomegaly, peripheral blood cytopenia of ≥2 lineages, hypertriglyceridemia and/or hypofibrinogenemia, hemophagocytosis without evidence of malignancy in bone marrow, spleen, or lymph nodes, elevated serum ferritin, low or absent natural killer (NK) cell activity, elevated soluble IL-2 receptor (soluble CD25)
What is first line therapy for patients with HLH?
Dexamethasone and etoposide. If CNS disease is present, methotrexate is given as well.
When is bone marrow transplant indicated in patients with HLH?
Bone marrow transplant is indicated in patients with primary HLH or children with secondary HLH who are refractory to chemotherapy, or who relapse.
