SIU School of Medicine

Interstitial Lung Disease in a Hot Tub User

By: Mouhammed Rihawi, M.D.
Senior fellow, Division of Pulmonary and Critical Care Medicine
Southern Illinois University School of Medicine, Springfield, Illinois, USA

Pradeep Kulkarni, MD
Central Illinois Allergy and Respiratory Services Ltd., Springfield, Illinois, USA

Lena Sherba MD
Associate Pathologist Ltd., Springfield, Illinois, USA

A 46 year old immunocompetent Caucasian female presented with a 2 week history of right sided chest discomfort, nonproductive cough, shortness of breath, and myalgias. Her shortness of breath was worse with activity and when lying down. She had no fever, chills, skin rash, or weight loss, and she denied any other complaints.

Her past medical history was significant for iron deficiency anemia, migraine headaches, eczema of bilateral hands, and an episode of severe acute bronchitis thirty years ago. There was no history of preexisting pulmonary disorders. Her medications included oral contraceptives and albuterol metered dose inhaler to be used as needed (the latter was given to her for a presumptive diagnosis of asthma since the onset of her symptoms). She denied cigarette smoking and illicit drug use, and had minimal alcohol use. She worked as a legal assistant and denied any unusual hobbies or occupational exposures. She kept two parakeets at home which were both healthy. She used an indoor hot tub at her home on a near daily basis for the last four years and had changed the water in the hot tub once or twice a year. Her family history was significant for coronary artery disease in her mother.

Her physical examination revealed a slender woman who did not appear ill with stable vital signs. She was in no obvious respiratory distress. She had fine bilateral inspiratory and expiratory crackles diffusely present in all lung fields on auscultation. In addition, she had mild scoliosis and eczema involving dorsa of bilateral hands.

Her chest radiograph showed bilateral interstitial infiltrates without any mediastinal or hilar lymphadenopathy. Her laboratory evaluation revealed a normal complete blood count, chemistry panel, B- type natriuretic peptide level, cardiac isoenzymes, and erythrocyte sedimentation rate. Her antinuclear antibody levels were normal. Her purified protein derivative (PPD) skin test showed less than 5 mm induration at 48 hours. Hypersensitivity pneumonitis screen was negative for the following antigens: Aspergillus fumigatus, Micropolyspora faeni, pigeon serum, thermophilic actinomycetes, and Saccharomonospora viridans. A spiral computerized tomography scan of her chest ruled out pulmonary embolism and revealed bilateral ground glass opacities with diffuse micro-nodular appearance (figure 1).

Figure 1: A spiral computerized tomography scan of her chest on presentation

Her pulmonary function tests (Table 1) showed a mild obstructive defect with air trapping and moderate decrease in CO diffusion capacity (51% of predicted).

Table 1: Pulmonary function test (PFT) on presentation

Pulmonary function test	Measured	Predicted *	Percent predicted
FVC	2.85	3.38	84
FEV1	2.08	2.81	74
FEV1/FVC	73	84
TLC	4.88	5.22	94
DLCO	10.5	20.4	51

* Predicted values were obtained using the Knudson’s reference equation.

Her clinical and radiologic picture did not improve even after the two parakeets were removed from her home. A subsequent bronchoscopy with bronchoalveolar lavage and transbronchial biopsy was done. The lavage revealed 75% lymphocytes and an unrevealing gram stain, GMS and acid fast bacillus (AFB) stain. Two weeks after the bronchoscopy, the lavage grew Mycobacterium avium complex (MAC). The transbronchial biopsy of the right upper lobe is shown in figure 2.

Figure 2: Lung, right upper lobe (H&E, 10 X and 40 X original magnification in Figures 2a and 2b respectively). The transbronchial biopsy of the right upper lobe showed several non-caseating granulomas (white arrows in Figure 2a) with multinucleated giant cells (black arrow in Figure 2b). No acid fast bacilli or fungal organism were identified on AFB and GMS stains respectively.

Figure 2a
Figure 2b

QUESTION 1:

Given the clinical history, which ONE of the following is the most likely diagnosis?

A - Sarcoidosis
B - Active diffuse MAC infection
C - Vasculitis
D - Asthma

QUESTION 2:

Inhalation of water contaminated with all of the following may cause hypersensitivity pneumonitis-like picture EXCEPT:

A - MAC
B - Thermophilic actinomycetes
C - Bromine and hydrobromic acid
D - Klebsiella oxytoca

QUESTION 3:

All of the following are clinicopathologic patterns of MAC infection EXCEPT:

A - Cavitary lung disease
B - Opportunistic infection with miliary disease
C - Small nodular infiltrates with bronchiectasis
D - Diffuse alveolar infiltrate with hypersensitivity pneumonitis-like pattern
E - Alveolar hemorrhage syndrome

QUESTION 4:

Which ONE of the following is the NEXT step in the management of this patient?

A - Abstinence from hot tub use
B - MAC antimicrobial therapy
C - A trial course of steroids
D - All of the above

QUESTION 5:

Which ONE of the following is true about the natural course of the disease?

A - Long term disability is common even after cessation of exposure
B - Recurrence is seen in most cases
C - Complete or near-complete recovery without relapse is the most common natural course
D - This disease predisposes to future MAC infections of the gastrointestinal tract and other systemic organs

SUGGESTED READING:

Seminars in Respiratory Infections Online: Aksamit TR. Hot tub lung: infection, inflammation, or both? (Requires paid access)

REFERENCES:

1 Cappelluti E, Fraire AE, Schaefer OP. A case of "hot tub lung" due to Mycobacterium avium complex in an immunocompetent host. Arch Intern Med 2003; 163:845-848
2 Aksamit TR. Hot tub lung: infection, inflammation, or both? Semin Respir Infect 2003; 18:33-39
3 Embil J, Warren P, Yakrus M, et al. Pulmonary illness associated with exposure to Mycobacterium-avium complex in hot tub water. Hypersensitivity pneumonitis or infection? Chest 1997; 111:813-816
4 Khoor A, Leslie KO, Tazelaar HD, et al. Diffuse pulmonary disease caused by nontuberculous mycobacteria in immunocompetent people (hot tub lung). Am J Clin Pathol 2001; 115:755-762
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8 Burns MJ, Linden CJ. Another Hot Tub Hazard. Toxicity Secondary to Bromine and Hydrobromic Acid Exposure. CHEST 1997; 111:816-819
9 Reich JM, Johnson RE. Mycobacterium avium complex pulmonary disease presenting as an isolated lingular or middle lobe pattern. The Lady Windermere syndrome. Chest 1992; 101:1605-1609

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