Langerhans cell histiocytosis - early stage

Clinical History

A 41-year-old man, with type 1 diabetes and a history of heavy smoking underwent a routine chest X-ray examination.

Imaging Findings

PA and lateral films were performed, revealing a nodular pattern projected over both lung fields, predominantly in the middle and upper zones, in a patient without respiratory symptoms.
Later, a contrast-enhanced CT scan was performed, confirming multiple small lung nodules bilaterally (<1cm). Some nodules appear solid while others show cavitation, dispersed in lung parenchyma but sparing most inferior segments. Additionally, mild hepatomegaly was visualised, with some hypodense nodules dispersed in the liver and spleen, measuring up to 13mm.
The patient underwent bronchofibroscopy and upper/lower GI endoscopy, which were all inconclusive.
The histological diagnosis was made by percutaneous transthoracic lung biopsy.

Discussion

Langerhans cell histiocytosis (LCH), formerly known as histiocytosis X, is a disease of unknown etiology [4], in which Langerhans cell accumulations involve one or more body systems (bone, lung, reticuloendothelial system, lymph nodes, skin, central nervous system, etc.). [2]
LCH is commonly seen in early childhood and middle-aged adults (20-40y). Its occurrence in adults is rare. [3]
Lung involvement in LCH is common, seen in 40% of patients. In adults, pulmonary LCH occurs primarily in smokers, with peak age at presentation between 30 to 40 years. Symptoms vary widely, from being asymptomatic to having severe dyspnoea. Up to 20% of patients present with pneumothorax. [1]
Abnormalities are usually bilateral, predominantly involving the upper and middle lung zones, sparing costophrenic angles. [2]
In the early stage, pulmonary LCH is characterised by small scattered lung nodules, mainly peribronchiolar, not exceeding 1cm, representing granulomas containing a large number of Langerhans cells and eosinophils. Over time, the lesions may regress spontaneously or progress with destruction of lung tissue, resulting in cavitation, and later be replaced by fibrosis and lung cysts. These cysts tend to be irregular, thick-walled, sometimes with bizarre shapes. Late disease may present with cysts that nearly replace normal lung, eventually becoming thin-walled. [1]
In adults, liver involvement in LHC is relatively frequent but often overlooked, with two distinct forms: early involvement with hepatomegaly and liver nodules (solid or cystic), usually responsive to treatment, and a second form with chronic fibrosis centred on bile ducts, progressing to sclerosing cholangitis. Prognosis is worst in LCH if the liver is involved.
The spleen is involved less frequently in LCH than the liver, and it’s also considered a risk organ. This may manifest with splenomegaly or spleen nodules, similar to liver involvement. [3]
Take-home message: Adult LCH is a rare disease but should be considered in the differential diagnosis of a middle-aged smoker with bilateral small cavitating lung nodules (relative sparing of lung bases) and liver/spleen involvement, in addition to other aetiologies like septic emboli, metastasis, granulomatosis with polyangiitis (Wegener), rheumatoid arthritis, and infection.

Differential Diagnosis List

Final Diagnosis

Langerhans Cell Histiocytosis

URL:	https://eurorad.org/case/15526
DOI:	10.1594/EURORAD/CASE.15526
ISSN:	1563-4086