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Published on: June 16, 2020
Familial idiopathic interstitial pneumonia: histopathology and survival in 30 patients
Kevin O Leslie1, Carlyne D Cool, Thomas A Sporn
1Department of Pathology, Mayo Clinic Arizona, 13400 East Shea Blvd, Scottsdale, AZ 85259, USA. Leslie.Kevin@mayo.edu
Context:
Familial idiopathic interstitial pneumonia (F-IIP) describes the unexplained occurrence of diffuse parenchymal lung disease in related individuals. Prevailing wisdom suggests that the histopathology of F-IIP is indistinguishable from that of idiopathic pulmonary fibrosis, namely, usual interstitial pneumonia (UIP).
Objective:
To define the histopathology of F-IIP in lung tissue samples.
Design:
Tissue sections from 30 patients with F-IIP, enrolled in a national research program, were evaluated by 3 pulmonary pathologists using 15 predefined histopathologic features. Each feature was recorded independently before a final diagnosis was chosen from a limited list dichotomized between UIP or "not UIP." These 2 groups were then compared to survival.
Results:
The consensus diagnosis for the F-IIP cohort was an unclassifiable parenchymal fibrosis (60%), with a high incidence of histopathologic honeycombing, fibroblast foci, and smooth muscle in fibrosis. Usual interstitial pneumonia, strictly defined, was identified in less than half of the F-IIP cases (range, 23%-50%). Interobserver agreement was fair (κ = 0.37) for 2 observers for the overall diagnosis of UIP. Findings unexpected in UIP were prevalent. The survival for the entire F-IIP cohort was poor, with an estimated mortality of 93% and a median age at death of 60.9 years. Subjects with UIP had a shorter survival and younger age at death.
Conclusions:
Pulmonary fibrosis was the dominant histopathology identified in our patients, but diagnostic features of UIP were seen in less than 50% of the samples. Overall survival was poor, with mortality accelerated apparently by the presence of a UIP pattern of disease.
Insights
Familial idiopathic interstitial pneumonia (F-IIP) often presents as unclassifiable fibrosis, not typical usual interstitial pneumonia (UIP). Survival is poor for F-IIP patients, with UIP patterns potentially accelerating mortality.
Area of Science:
- Pulmonology
- Pathology
- Genetics
Background:
- Familial idiopathic interstitial pneumonia (F-IIP) is diffuse lung disease in relatives.
- It is often presumed to have the same histopathology as idiopathic pulmonary fibrosis (IPF), specifically usual interstitial pneumonia (UIP).
Purpose of the Study:
- To define the histopathology of F-IIP in lung tissue samples.
- To compare F-IIP histopathology with UIP criteria.
- To correlate histopathology with survival outcomes in F-IIP.
Main Methods:
- 30 F-IIP patients' lung tissue samples were analyzed by 3 pathologists.
- 15 predefined histopathologic features were assessed.
- Diagnoses were dichotomized as UIP or not UIP and compared to survival data.
Main Results:
- 60% of F-IIP cases were unclassifiable fibrosis, with frequent honeycombing, fibroblast foci, and smooth muscle.
- Strict UIP diagnosis was found in less than 50% of F-IIP cases.
- Interobserver agreement for UIP diagnosis was fair (κ=0.37).
- F-IIP cohort survival was poor (93% mortality, median age at death 60.9 years).
- UIP pattern was associated with shorter survival and younger age at death.
Conclusions:
- Pulmonary fibrosis is dominant in F-IIP, but UIP features are present in less than half of cases.
- F-IIP histopathology is often distinct from strictly defined UIP.
- Poor survival in F-IIP is confirmed, with UIP patterns potentially worsening outcomes.
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