Idiopathic Familial Pulmonary Fibrosis

Pathology and Pathogenesis

There is a small subset of patients with IPF who have a history of unexplained lung disease in Þrst-degree relatives. This form of pulmonary Þbrosis has been referred to as familial IPF or familial interstitial pneumonia. Genetic analysis was performed in search of the mechanism underlying familial IPF, and telomerase germ line mutations were identiÞed in 8 %. The role of telomerase mutations was hypothesized to be a function of excess telomere shortening over time, resulting in cellular dysfunction and premature cell death [25].

Symptoms and Signs

The clinical features of familial IPF are indistinguishable from sporadic form of IPF, but the age at diagnosis is signiÞcantly younger [26].

CT Findings

Like sporadic IPF, characteristic thin-section CT (TSCT) Þndings of familial IPF include areas of ground-glass opacity (GGO), intralobular reticular opacity, irregular thickening of the interlobular septa, traction bronchiectasis, and small foci of consolidation. HC is seen in approximately one-third of patients, and lung lesions demonstrate still lower lung zone predominance (67 %, 6 of 9 patients). However, upper lung zone predominance (33 %) is higher than nonfamilial IPF [21] (Fig. 17.5).

CT–Pathology Comparisons

Please, refer to section ÒHoneycombing with Subpleural or Basal PredominanceÓ.

Patient Prognosis

Overall prognosis of familial IPF is not well known, but pulmonary Þbrosis associated with telomerase gene mutations has been reported to be progressive and lethal with a mean survival of 3 years after diagnosis [27].

Chronic Hypersensitivity Pneumonia

Pathology and Pathogenesis

The Þbrosis pattern in chronic HP, which exhibits a predominantly UIP-like pattern histologically, is characterized by centrilobular Þbrosis, bridging Þbrosis, and intraluminal Þbrosis, in addition to the subpleural and paraseptal Þbrosis that is seen commonly in UIP cases. Bronchiolar alterations in patients with chronic HP are characterized by lymphoid aggregates, occasional granulomas or giant cells, and Þbroblastic foci in the respiratory bronchioles [28].

Symptoms and Signs

Chronic HP manifests as slowly progressive shortness of breath, cough, fatigue, malaise, and weight loss [29]. It frequently results in severe irreversible physiologic impairment due to lung Þbrosis. History of acute episodes of HP is usually