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Respiratory Medicine Case Reports 12 (2014) 19e21

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Respiratory Medicine Case Reports

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Case report

Blizzard Sign as a specific endobronchial ultrasound image for groundglass opacity: A case report

Shinji Sasada, M.D. Ph.D. *, Takehiro Izumo, M.D. Ph.D., Christine Chavez, M.D.,Takaaki Tsuchida, M.D. Ph.D.Department of Endoscopy, Respiratory Endoscopy Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan

Keywords:Endobronchial ultrasound with a guidesheathGround glass opacityPeripheral pulmonary lesionBlizzard Sign

Abbreviation: AIS, adenocarcinoma in situ; CT, coendobronchial ultrasound; EBUS-GS, endobronchiasheath; GGO, ground glass opacity; MIA, minimally inperipheral pulmonary lesion; TBB, transbronchial bio* Corresponding author. Tel.: þ81 3 3542 2511; fax

E-mail address: sasastaf@hotmail.co.jp (S. Sasada)

http://dx.doi.org/10.1016/j.rmcr.2013.11.0032213-0071 � 2014 The Authors. Published by Elsevier

a b s t r a c t

We report a case of lung adenocarcinoma presenting as pure ground glass opacity (GGO) and diagnosedby bronchoscopy with the use endobronchial ultrasound with a guide sheath (EBUS-GS). The lesion wasindistinguishable by real-time fluoroscopy but simultaneous endobronchial ultrasound scanning of theinvolved lung segment showed a hyperechoic shadow that was subtly more intense than a typicalsnowstorm appearance when scanning normal alveolar tissue. Transbronchial biopsy from this arearevealed adenocarcinoma with lepidic growth.

On hindsight, it was the aforementioned ultrasound pattern that helped us decide the sampling site forEBUS-GS guided TBB when fluoroscopy was equivocal. We hypothesize that this pattern is specific forGGO and we name it the Blizzard Sign.

� 2014 The Authors. Published by Elsevier Ltd. Open access under CC BY-NC-ND license.

Introduction

Transbronchial biopsy (TBB) with the aid of radial endobron-chial ultrasound (R-EBUS) had long been demonstrated to have agood diagnostic performance for peripheral pulmonary lesions(PPL) [1]. Almost 10 years ago, Kurimoto et al. introduced endo-bronchial ultrasound with a guide sheath (EBUS-GS) to augmentTBB [2] and indeed, the overall diagnostic yield for PPLs increasedto 70 percent [3].

A lung adenocarcinoma that presents as ground glass opacity(GGO) on computed tomography (CT) screening is often detectedthese days [4], but majority of the patients either undergo surgicalresection or are observed without definitive diagnosis. However,diagnostic bronchoscopy for GGO lesions, especially the pure typewithout a solid component, is not commonly performed becausemost respiratory physicians recognize that GGO cannot be visual-ized on fluoroscopy or is undetectable by EBUS. In fact, severalstudies on bronchoscopic diagnosis of solid pulmonary noduleshave already been published but only a few studies on GGO werereported [5].

mputed tomography; EBUS,l ultrasound with a guidevasive adenocarcinoma; PPL,psy.: þ81 3 3542 3567..

Ltd. Open access under CC BY-NC-ND

Performing EBUS-GS for TBB of GGO is a challenging matter.To the best of our knowledge, an EBUS finding that represents aground glass process is still unknown. In this case report, wedescribe the specific EBUS findings for GGO and highlight theimportance of obtaining large pieces for definitive diagnosis.

Case presentation

The representative case is that of an 81-year old female, non-smoker, with a 35 mm pure ground glass opacity (GGO) in theright lower lobe that was incidentally seen on computed to-mography (CT) scan of the chest (Fig. 1A) but was indistinct onchest radiograph (Fig. 1B). The endobronchial route was carefullyplanned prior to bronchoscopy using 1-mm cross-sectional CTscan images and the topographical location of the target lesion onthe coronal plane was mapped out on chest tomosynthesis. Thepatient underwent diagnostic bronchoscopy (1T260, Olympus)using radial EBUS (UM-S20-20R, Olympus) with large type GS (K-203, Olympus). Fluoroscopy was used concomitantly with endo-bronchial ultrasound scanning to find the target. During theinitial attempt, it was difficult to distinguish the mass on fluo-roscopy (Fig. 2A) and ultrasound signals only generated a snow-storm appearance that was ascribed as normal lung tissue(Fig. 2B). But we were certain that we were in the intended lungsegment so the ultrasound probe was inserted more distally. Atthis point, a subtle but noticeable enhancement and increase in

license.

Fig. 1. A. Computed tomography scan of the chest shows pure ground glass opacity on segment 8 of the right lung. B. On chest radiograph (PA view), note that the area corre-sponding to right lung segment 8 does not clearly define an abnormality.

Fig. 2. A. Real-time fluoroscopy image of the chest during endobronchial ultrasound scanning. B. Initial endobronchial ultrasound scanning through the right B8bi showed a whitishacoustic shadow that represented normal air-filled alveoli. EBUS image shown is on a 2 mm scale. C. The Blizzard Sign. When the endobronchial ultrasound probe was insertedfurther and more distally, there was a subtle but noticeable increase in the intensity and radius of the whitish acoustic shadowmore than 1 cm from the center of the EBUS image. D.Real-time fluoroscopy image during transbronchial biopsy using forceps and guide sheath (K-203 kit, Olympus).

S. Sasada et al. / Respiratory Medicine Case Reports 12 (2014) 19e2120

area of the snowstorm appearance was seen (Fig. 2C). Aftermarking this location of the GS on fluoroscopy, seven TBB sampleswere obtained using a dedicated biopsy forceps with guide sheathkit (Fig. 2D). Histopathologic examination of the 3rd to the 7thconsecutive biopsy specimens revealed adenocarcinoma withlepidic growth (Fig. 3). The patient was staged as T2aN0M0 butrefused further treatment.

Discussion

In this case report, the EBUS image of the pure GGO lesion wasan ill-defined signal that was more intense than the snowstormappearance of normal lung tissue. Using this as a confirmation ofthe desired GS location, we were able to successfully diagnose thetumor by TBB. When lesions in the lung adenocarcinoma spectrum

have a ground glass component, majority of the lesions arepathologically classified as either one of the following: adenocar-cinoma in situ (AIS), minimally invasive carcinoma (MIA), andlepidic predominant adenocarcinoma [6]. Based on our pre-liminary, unpublished data, 80% (12 out 15) of patients with GGO,who were diagnosed by EBUS-GS and surgically confirmed as AIS,MIA, or lepidic predominant adenocarcinoma, had EBUS findingsthat were similar to this report. The average number of specimensthat we obtained in this series and what we also recommend is atleast five.

We observed that this EBUS pattern for GGO has several char-acteristics. First, the change in the ultrasound signal from normallung tissue to the ground glass area is similar to a whiteout, albeitsubtle. Second, this signal traverses an area that is greater than thatof normal alveolar tissue. Based on our experience, the radius from

Fig. 3. Photomicrographs of the Hematoxylin & Eosin staining of a transbronchial biopsy specimen from a pure ground glass opacity show adenocarcinoma with lepidic growth. A(�100); B (�400).

S. Sasada et al. / Respiratory Medicine Case Reports 12 (2014) 19e21 21

the probe to the periphery of the acoustic shadow is usually morethan 1 cmwhile that of the surrounding normal lung parenchyma isless than 1 cm. Third, the character of the signals are generallymorecoarse compared to the typical snowstorm appearance. We desig-nated the name Blizzard Sign for this combination of characteristicsas a specific EBUS finding for GGO.

GGO patterns on CT scan are divided into pure, heterogeneous,or mixed type. In mixed type GGO, the solid component is generallydetected on EBUS scanning as a well-defined signal with hyper-echoic dots. The ground glass attenuation usually surrounds theperiphery of the lesion and demonstrates the Blizzard Sign justdescribed.

In this case, definitive diagnosis was successfully obtained fromseven TBB specimens by using the usual 1.8 mm biopsy forcepsincluded in the K-203 Guide Sheath Kit (Olympus). We underscorethe importance of using this biopsy forceps, particularly for pureGGO, to preserve the structural integrity of the tissues. We supposethat doing so would facilitate a more comprehensive histopatho-logic examination of the ground glass tissue sample, especially foridentifying AIS or MIA, which often exhibit weak cellular atypia.Most physicians commonly use small guide sheath kit (K-201)when approaching peripheral lesions but from our experience itoften fails to provide adequate amount of tissues. A usual 1.8 mmbiopsy forceps with large guide sheath (K-203) is favored inobtaining the desired quality of specimens compared to the smallone.

In conclusion, Blizzard Sign on EBUS was found to be useful fordetecting GGO, especially the pure type, during bronchoscopy evenif the lesion was not visualized by fluoroscopy.

Ethical issues

This study was approved by the hospital’s Institutional ReviewBoard and Ethics Committee; informed consent was sought fromthe patients.

Acknowledgment

We thank Koji Tsuta and Yukio Watanabe for pathological ex-aminations. This work was supported by The National CancerCenter Research and Development Fund (25-A-12).

References

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