Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Histiocytosis-X (Langerhans Cell Histiocytosis)
- Radiologic Findings
- Chest PA radiograph shows ill-defined nodular opacities with subtle reticular opacity in both upper lung zones. HRCT scans show multiple cavitary nodules and air-containing cysts with variable thickness of smooth wall in both upper and mid-lung zone, sparing both lower lung zones. Diagnosis of Histiocytosis-X was made by open lung biopsy.
- Brief Review
- The pathogenesis of the pulmonary lesions of histiocytosis X (HX) is poorly understood. HX exhibited cysts scattered throughout the lung parenchyma. In almost all patients, HRCT demonstrates cystic air spaces, which are usually less than 10 mm in diameter; these cysts are characteristic of HX. On HRCT, the lung cysts have walls that range from being barely perceptible to being several millimeters in thickness. The presence of distinct walls allows differentiation of these cysts from areas of emphysema. Although many cysts appear round, they can also have bizarre shapes, being bilobed, clover-leaf shaped, or branching in appearance. Confluent or conjoined cysts with persisting septations are seen in more than two thirds of patients. HRCT findings closely mirror the gross pathologic appearances of this disease. The cysts were lined with fibrous tissue, which interrupted focally by a diverse population of inflammatory cells and histiocytes. Interstitial cellular infiltration is associated with destruction and retraction of the lung parenchyma, which appeared to result in the formation of new cystic spaces. The Langerhans' histiocyte may play a role in the production of fibrous tissue in the early formation of cyst walls. The mechanism of cystic changes is uncertain. Patterns of the nodules or cysts may represent longevity of the lesions. Early stage of the disease is characterized by the abundance of nodules and cavitated nodules, whereas cysts are few and do not tend to be confluent. Advanced disease is characterized by a small number of nodules, whereas cysts have increased in number and size and are confluent. The following sequence of abnormalities seen with CT corresponds to the evolution of the disease: nodules, cavitated nodules, thick-walled cysts, cysts, and confluent cysts, rupture or collapse of cysts with or without pneumothorax.
Summary of HRCT findings in Histiocytosis X
1. thin-walled lung cysts, some confluent or with bizarre shapes, usually less than 1 cm
2. nodules, usually < 1-5mm, some centrilobular and peribronchiolar
3. upper-lobe predominance, costophrenic angles spared
4. cavitary nodules
5. fine reticular opacities, ground-glass opacity
- References
- 1. Brauner MW, Grenier P, Mouelhi MM, Mompoint D, Lenoir S. Pulmonary histiocytosis X: evaluation with HRCT. Radiology 1989;172:255-258
2. Moor ADA, Godwin DJ, Muller NL, et al. Pulmonary histiocytosis X: comparison of radiographic and CT findings. Radiology 1989;172:249-254}
3. Webb WR, Muller NL, Naidich DP. High-resolution CT of the lung. 2 ed. Philadelphia: Lippincott-Raven, 1996:227-231
- Keywords
- Lung, Idiopathic interstitial pneumonia, LCH, smoking related ILD, Histiocytosis-X (Langerhans Cell Histiocytosis)