In LCH, the liver and spleen are considered high-risk organs, and involvement of these organs affects prognosis. Involvement in this context means the liver and spleen are enlarged from direct infiltration of LCH cells or as a secondary phenomenon of excess cytokines, which cause macrophage activation or infiltration of lymphocytes around bile ducts. LCH has a portal (bile duct) trophism that leads to biliary damage and ductal sclerosis. A percutaneous (peripheral) liver biopsy may not be diagnostic of the infiltrate that tends to be more central in the liver, but will show the upstream obstructive effects of distal biliary occlusion. Hepatic enlargement can be accompanied by dysfunction, leading to hypoalbuminemia with ascites, hyperbilirubinemia, and clotting factor deficiencies. Sonography, computed tomography (CT), or MRI of the liver will show hypoechoic or low-signal intensity along the portal veins or biliary tracts when the liver is involved with LCH.
Liver (sclerosing cholangitis)
One of the most serious complications of hepatic LCH is cholestasis and sclerosing cholangitis. This usually occurs months after initial presentation, but on occasion may be present at diagnosis. The median age of children with this form of hepatic LCH is 23 months.
Patients with hepatic LCH present with hepatomegaly or hepatosplenomegaly, and elevated alkaline phosphatase, liver transaminases, and gamma glutamyl transpeptidase levels. Biopsies show no LCH cells but infiltrating lymphocytes surrounding the bile ducts may be present. It is thought that cytokines, such as TGF-beta, elaborated by lymphocytes during the active phase of the disease, leads to fibrosis and sclerosis around the bile ducts.
Seventy-five percent of children with sclerosing cholangitis will not respond to chemotherapy because the LCH is no longer active, but the fibrosis and sclerosis remain. Liver transplantation is the only alternate treatment when hepatic function worsens. In one series of 28 children undergoing liver transplantation, 78% survived and 29% had recurrence of LCH but only two cases of recurrent LCH occurred in the transplanted liver. The patients who undergo liver transplant for LCH may have a higher incidence of posttransplant lymphoproliferative disease.
Massive splenomegaly may lead to cytopenias because of hypersplenism and may cause respiratory compromise. Splenectomy typically provides only transient relief of cytopenias, as increased liver size and reticuloendothelial activation results in peripheral blood cell sequestration and destruction. Although rare, LCH infiltration of the pancreas and kidneys has been reported. Splenectomy is only performed as a life-saving measure.
Other gastrointestinal manifestations
A few patients with diarrhea, hematochezia, perianal fistulas, or malabsorption have been reported.[18,19] Diagnosing gastrointestinal involvement with LCH is difficult because of patchy involvement. Careful endoscopic examination including multiple biopsies is usually needed.
In LCH, the lung is also considered a high-risk organ, but is less frequently involved in children than in adults, in whom smoking is a key etiologic factor. The cystic/nodular pattern of disease reflects the cytokine-induced destruction of lung tissue. Classically, the disease is symmetrical and predominates in the upper and middle lung fields, sparing the costophrenic angle and giving a very characteristic picture on high-resolution CT scan. Confluence of cysts may lead to bullous formation and spontaneous pneumothorax can be the first sign of LCH in the lung, although patients may present with tachypnea or dyspnea. Ultimately, widespread fibrosis and destruction of lung tissue leads to severe pulmonary insufficiency. Declining diffusion capacity may also herald the onset of pulmonary hypertension. In young children with diffuse disease, therapy can halt progress of the tissue destruction and normal repair mechanisms may restore some function. However, adults who have progression with diffuse bullae formation, multiple pneumothoraces, and fibrosis have a poor prognosis.[22,23]