CT findings of probable UIP have a high predictive value for histologic UIP
Chung JH, Chawla A, Peljto AL, Cool C, Groshong SD, Talbert JL, McKean D, Brown KK, Fingerlin TE, Schwarz MI, Schwartz DA, Lynch DA.
Chest. 2014 Oct 9. doi: 10.1378/chest.14-0976.
The current UIP/IPF CT classification system excludes probable UIP as a diagnostic category. We sought to determine the predictive effect of probable CT UIP on histology, and to determine the effect of the promoter polymorphism in the MUC5B gene (rs35705950) on histologic and CT UIP diagnosis.
The cohort included 201 subjects with pulmonary fibrosis who had lung tissue samples obtained within one year of chest CT. UIP diagnosis on CT was categorized as inconsistent with, indeterminate, probable, or definite UIP by 2-3 pulmonary radiologists. Tissue slides were scored by two expert pulmonary pathologists. All subjects with available DNA (N=200) were genotyped for rs35705950.
The proportion of CT diagnoses were as follows: inconsistent with 69/201 (34.3%), indeterminate 72/201 (35.8%), probable 34/201 (16.9%), and definite 26/201 (12.9%) UIP. Subjects with probable CT UIP were more likely to have histologic probable/definite UIP than subjects with indeterminate CT UIP (82.4% [28/34] versus 54.2% [39/72]; p-value 0.01). CT and microscopic honeycombing were not associated with each other (p-value 0.76). The minor (T) allele of the MUC5B polymorphism was associated with concordant CT and histologic UIP diagnosis (p-value: 0.03).
Probable CT UIP is associated with a higher rate of histologic UIP than indeterminate CT UIP suggesting that they are distinct groups and should not be combined into a single CT category as currently recommended by guidelines. CT and microscopic honeycombing may be dissimilar entities. The T allele at rs35705950 predicts a UIP diagnosis by both chest CT and histology.