Table 3.
Criteria for classifying hot tub lung as HP (Lacasse et al. 2003).
| Criteria for diagnosis of HP | Comments related to hot tub lung |
|---|---|
| Significant clinical predictors | |
| Evidence of exposure to a known offending antigen | History of hot tub/spa pool/shower exposure in all patients (100%); isolation of antigen in sputum (74.1%); BALF (62.5%); lung biopsy (85.7%); hot tub/source (94.7%) |
| Positive precipitating antibodies | Not identified in serum and/or BALF |
| Recurrent episodes of symptoms | Described with recurrent exposures (Cappelluti et al. 2003; Embil et al. 1997) |
| Inspiratory crackles | Described in 17/36 cases (47.2%) |
| Symptoms 4–8 hr after exposure | Usually subacute presentation, acute onset of symptoms after exposure described in a minority (Embil et al. 1997) |
| Weight loss | Described in 20% cases |
| Gold standard for accepting diagnosis without additional procedures | |
| Presence of both BALF lymphocytosisa and bilateral ground glass or poorly defined centrilobular nodular opacities on HRCT scan of the chest | BALF lymphocytosisa seen in 8/8 cases (100%) and HRCT abnormalities seen in 40/40 cases (100%) |
| Pathological criteria for accepting the diagnosis | |
| Presence of chronic inflammatory infiltrates along small airways and interstitium (diffuse), and scattered, small, nonnecrotizing granulomas | Seen in 41/41 cases with reported histopathology as defined (100%) |
a
BALF lymphocytosis defined as ≥ 30% for nonsmokers and ex-smokers and ≥ 20% for current smokers.