Pulmonary Langerhans cell histiocytosis
The patient arrived at the hospital emergency room due to pain in the lower limbs and functional impotence. She had smoked for 20 years but did not report current respiratory symptoms. CT is routinely requested as the first imaging study in the context of the COVID 19 pandemic, which is why chest X-ray was not performed.
In the presence of pulmonary cysts, the differential diagnosis includes lymphangioleiomyomatosis (LAM) and lymphocytic interstitial pneumonia (LIP). In addition, history such as immunodeficiency and tobacco use should be investigated.
Lymphangioleiomyomatosis also presents with multiple cysts with thin walls, possibly coalescent, with diffuse homogeneous distribution but with a predominant apical distribution. There may be centrilobular nodules. In Langerhans cell histiocytosis, on the other hand, cavitating nodules, initially thick-walled and spherical in morphology, occur in combination with centrilobular nodules. They evolve into thin-walled cysts, then coalesce in advanced stages, acquiring tubular morphology or irregular contour partly due to traction from the presence of fibrosis, and must be differentiated from bullous emphysema. In the final stages, a “burned” lung is described, very similar to emphysema, with increased volume, plus a reticular pattern due to fibrosis. An important characteristic is that this evolution is of upper lung predominance.
In the histopathological study of the piece obtained by transbronchial biopsy, there were cells with a histiocytic appearance and occasional multinucleated giant cells were found. Immunohistochemistry was positive for S100, CD1a and CD68.
The images of this patient were evaluated together with Dr. Agustina Regallo, a colleague from the Diagnostic Imaging Service, and Dr. Javier Abdala, Pulmonary Specialist.