- • Nonproductive cough and dyspnea with or without
- • Extrathoracic involvement (5–15%)
of bones, skin, hypothalamus, liver, spleen, and lymph nodes.
- • Nodular or cystic pattern on high-resolution computed
tomography with basal sparing.
- • Demonstration of Langerhans’ cells and
bronchiolocentric granuloma on lung biopsy or increased (>5%)
CD1a-positive cells on bronchoalveolar lavage.
Pulmonary Langerhans’-cell histiocytosis (PLH) is part
of a spectrum of diseases characterized by proliferation of and
infiltration by Langerhans’ cells into various organs.
Several organ systems may be involved in Langerhans’-cell
histiocytosis (LCH), including the lungs, bone, skin, pituitary
gland, liver, lymph nodes, and thyroid (Figure 14–1).
Lung involvement may occur either in isolation or as part of a multisystem
syndrome. When lung disease is part of the clinical presentation
in adult patients, the term pulmonary Langerhans’-cell
histiocytosis is used.
Organ involvement in Langerhans’-cell hystiocytosis
The nomenclature of these syndromes is diverse. Older classification
schemes used designations such as systemic histiocytosis X, eosinophilic
granuloma, Letterer–Siwe disease, Hand–Schuller–Christian
syndrome, Hashimoto–Pritzker syndrome, and Langerhans cell
granulomatosis. To avoid confusion due to eponymous conflicts, the
Histiocyte Society established a simplified classification scheme
based on a spectrum of presentations that varies from those involving
single organs to more aggressive, disseminated disease. These diseases
should be referred to as Langerhans’-cell histiocytosis
and the presence of specific organ involvement should be described.
In patients with pulmonary manifestations, the lung is the only
organ system affected in approximately 85%, whereas multisystem
disease is seen in 5–15%.
The exact prevalence and incidence of PLH are unknown. However,
it appears that this is a rare disease. In one study of those undergoing
open-lung biopsy for interstitial lung disease, only 15 cases of
PLH were detected among 501 patients over 6 years, whereas 274 cases
of sarcoidosis were found. Another study of biopsy specimens from
patients with interstitial lung disease found PLH in 5%.
However, it has been suggested that PLH may be underdiagnosed as
some patients have a paucity of symptoms or undergo a spontaneous
remission and never undergo a confirmatory biopsy.
There does not seem to be a familial basis to PLH. The specific
genetic factors involved are not known. It appears to be a disease
largely of white individuals with no specific geographic predilection.
Likely, there is no gender predominance. Early series suggested
a male bias, but more recent series have called this into question.
Changing patterns in tobacco consumption, with more women now smoking,
may have caused this apparent shift. Most patients are between 20
and 40 years of age, but pulmonary involvement has been described
in individuals from 3 months to 69 years of age.
The one identifiable and consistent risk factor for PLH is cigarette
smoking. In ...