Author Daniel Kotok, MD1, Anas Hadeh, MD1 Department of Pulmonary and Critical Care Medicine Cleveland Clinic Florida, Weston, FL
Case
A 71-year-old female presents to our pulmonary clinic for evaluation
of abnormal computed tomography (CT) chest obtained as part of routine
pre-transplant evaluation for end-stage renal disease secondary to
isolated pauci-immune glomerulonephritis. She was not treated for this
because of end-stage disease at time of diagnosis and isolated renal
involvement. Age-appropriate screening is normal. She has no respiratory
symptoms and has never smoked. There are two cats and two birds at her
household. Vital signs are notable for a BMI of 17.8. Physical exam is
otherwise normal. Routine labs including complete blood count and
complete metabolic panel were unrevealing. Antineutrophil cytoplasmic
antibodies (ANCA, myeloperoxidase and proteinase 3) were not detected.
Interferon-gamma release assay (IGRA) was negative. No allergen-specific
testing has been performed.
Images
Question
What is the most likely diagnosis?
A. Hypersensitivity pneumonitis B. Pulmonary granulomatosis with polyangiitis C. Metastatic cancer D. Non-tuberculous mycobacterial infection
Answer
D. Non-tuberculous mycobacterial infection
Discussion
Non-tuberculous mycobacteria are a large group of soil and
water-inhabiting bacteria encompassing over 150 species with varying
degrees of virulence and predilection for patients with certain comorbid
conditions such as pre-existing lung disease and immunodeficient
states. In North America, the prevalence of NTM is higher in the
Southeastern region stretching from Texas to Florida (1).
A distinct phenotype of patients with NTM infection has been dubbed
“Lady Windermere syndrome” (2), named after the heroine of a play
written by Oscar Wilde known for her propensity for elegance
necessitating chronic cough suppression. The prototypical patient is a
post-menopausal, thin woman with disease involving the right middle lobe
and lingula.
Some of the radiographic characteristics, although not specific for
NTM infection, include centrilobular nodules (orange arrow), tree-in-bud
opacities (orange arrowhead) bronchiectasis affecting the right middle
lobe and lingula (yellow arrow), consolidation (seen in axial CT above)
and cavitation. (1, 2)
Epidemiologic risk factors for NTM infection overlap with those of tuberculous
mycobacterial infection (i.e. tuberculosis, TB), including higher risk
of infection in immunosuppressed patients, in those with renal
dysfunction, poor nutritional status (particularly in those with BM <
18.5) and older age in developed countries among others. (3) As such,
exclusion of this diagnosis and appropriate patient isolation and
collection and handling of specimens in suspected cases is important in
the prevention and spread of TB.
Hypersensitivity pneumonitis (A) can present with various
radiographic findings on CT depending on the stage of the disease,
ranging from scarce centrilobular nodules, homogenous ground-glass
opacities (GGO) and areas of hypoattenuation and hypovascularity in a
“mosaic attenuation” to usual interstitial pneumonitis with advanced
fibrosis (4). The lack of GGOs, scarcity of nodules and presence of
bronchiectasis and consolidation argue against this diagnosis.
Pulmonary involvement in granulomatosis with polyangiitis (B, also
known as Wegener's granulomatosis) is common and seen in up to 90% of
patients. Clinical and radiographic abnormalities are highly variable.
Commonly described radiographic abnormalities include nodules with
various sizes in a random distribution relative to the secondary
pulmonary nodule with or without cavitation, pulmonary hemorrhage and
wedge consolidation among others (5). While this diagnosis cannot be
entirely excluded without biopsy demonstrating non-necrotizing
granulomas, the lack of pulmonary symptoms, negative ANCAs and presence
of microbiologic evidence of NTM make this diagnosis less likely.
Lastly, metastatic cancer (C) commonly presents as multiple
peripheral nodules with or without evidence of lymphangitic spread.
Although the appearance and location of radiographic abnormalities
varies depending on the primary site of malignancy, localized grouping
of nodules is not characteristic of metastatic disease (6). In this
asymptomatic patient with normal age-appropriate screening, the
diagnosis of metastatic disease is unlikely.
As part of her further evaluation, the patient underwent
bronchoalveolar lavage demonstrating the presence of non-nocardia
acid-fast bacilli in samples obtained from the right middle lobe with
culture growing Mycobacterium avium complex 12 days after the procedure,
thus confirming the diagnosis of NTM.
References
Griffith DE et al. An official ATS/IDSA statement: Diagnosis, treatment, and prevention of nontuberculous mycobacterial diseases. Am J Respir Crit Care Med 2007;
Haworth CS et al. British Thoracic Society guidelines for the management of non-tuberculous mycobacterial pulmonary disease (NTM-PD). Thorax 2017;
Cahuayme-Zuniga LJ, Brust KB. Mycobacterial Infections in Patients With Chronic Kidney Disease and Kidney Transplantation. Adv Chronic Kidney Dis 2019;
Silva CIS, Churg A, Müller NL. Hypersensitivity Pneumonitis: Spectrum of High-Resolution CT and Pathologic Findings. Am J Roentgenol 2007;188:334–344.
Martinez F et al. Common and uncommon manifestations of Wegener granulomatosis at chest CT: Radiologic-pathologic correlation. Radiographics 2012;32:51–69.
Seo JB, Im JG, Goo JM, Chung MJ, Kim MY. Atypical pulmonary metastases: Spectrum of radiologic findings. Radiographics 2001;21:403–417.
