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Case Letter

Starry sky sign in endobronchial ultrasound of mediastinal lymphadenopathy

Gupta, Nitesh; Najeeb, Ramees; Shamil, PK; Ish, Pranav

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doi: 10.4103/lungindia.lungindia_539_21
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Sir,

A 15-year-old male presented with dry cough for 5 months and low-grade fever with evening rise of temperature for 1 month duration. There was no associated significant weight loss or loss of appetite. Clinical examination was normal. Chest X-ray showed mediastinal widening and prominence of right paratracheal stripe. A Mantoux test returned positive; however, induced sputum was negative for Mycobacterium tuberculosis. Subsequent contrast-enhanced computed tomography scan of thorax showed conglomerated mediastinal lymphadenopathy [Figure 1a] involving right upper and lower paratracheal, subcarinal, and right hilar nodes (size 3 cm × 5 cm). The nodes showed heterogeneous contrast enhancement and internal calcification. Lung parenchyma showed no significant abnormalities. Endobronchial ultrasound (EBUS)-guided transbronchial needle aspiration (TBNA) was planned for diagnosis. EBUS images of paratracheal and subcarinal lymph nodes showed multiple hyperechoic foci suggestive of a “starry sky sign” [Figure 1b]. Cytology samples revealed caseous material having epithelioid cell granulomas with background lymphocytic infiltrate. A diagnosis of tubercular lymphadenitis was made and the patient was treated with antitubercular therapy.

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Figure 1:
Computed tomography chest showing large subcarinal and hilar lymphadenopathy (a) Starry-sky sign in endobronchial ultrasound imaging of subcarinal lymph node (b)

Multiple hyperechoic foci without an acoustic shadow over a hypoechoic background in a lymph node give rise to a “starry sky sign.” These hyperechoic foci may represent granulomatous foci within the nodes and have high specificity. In a retrospective cohort study evaluating 31 tuberculous lymph nodes using EBUS-TBNA, the sensitivity and specificity of this sign were 51.6% and 100%, respectively.[1] Recent studies have suggested the use of endoscopic sonography in differentiating mediastinal benign (tuberculosis or sarcoidosis) lymph nodes from malignancy. Well-defined margins, large size, round shape, heterogenous, coagulation necrosis, peripheral neovascularization in color power Doppler, blue elastography image, and absence of central hilar structure are features documented to be associated with malignant etiology with varying sensitivity and specificity.[2] Among tuberculosis and sarcoidosis, which is often the diagnostic dilemma in our nation, heterogenous structure, smaller size, and necrosis are more common in tuberculosis.[3] Even though a pathological diagnosis is a must due to limited accuracy and specificity of EBUS-TBNA ultrasound features, the clinical and practical utility of these features is that they can provide collaborative evidence and help in choosing the lymph node station and the lymph node to sample within a station for diagnosing malignant or tubercular lymphadenitis based on clinical suspicion.

Informed consent

Written informed consent was taken from the patient.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

REFERENCES

1. Alici IO, Demirci NN, Yilmaz A, Karakaya J, Erdogan Y Starry sky sign:A prevalent sonographic finding in mediastinal tuberculous lymph nodes Endosc Ultrasound 2015 4 225–8
2. Agrawal SP, Ish P, Goel AD, Gupta N, Chakrabarti S, Bhattacharya D, et al Diagnostic utility of endobronchial ultrasound features in differentiating malignant and benign lymph nodes Monaldi Arch Chest Dis 2018 88 928
3. Erol S, Anar C, Erer OF, Biçmen C, Aydoğdu Z The contribution of ultrasonographic characteristics of mediastinal lymph nodes on differential diagnosis of tuberculous lymphadenitis from sarcoidosis Tanaffos 2018 17 250–6
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