Squamous cell carcinoma of lung presenting as “Sunray sign” in chest radiograph

INTRODUCTION

Sunray signs in chest radiographs are not very frequently described in medical literature, especially in cases with lung cancer. Interestingly, the Sunray sign is easily picked up during routine chest radiology examinations. Hilar mass with peripheral linear opacities spreading from margins of opacity is a sunray sign. We have documented this unique sign in bronchogenic carcinoma of squamous cell histological type.

CASE REPORT

A 51-year-old male, farmer, smoker, normotensive, and non-diabetic, was referred to our center by a family physician for complaints of dry cough with hemoptysis, shortness of breath on routine work, and dull aching retrosternal pain. Family members said that he was treated with intravenous antibiotics for 7 days by a family physician and showed poor response to antibiotics and other supportive care during hospitalization. Chest X-ray done by the family physician documented left hilar opacity [Figure 1]. We have clearly noted the “Sunray sign” in chest radiograph, that is, left hilar mass or radiopacity with inhomogeneous linear opacities spreading toward peripheries like sunrays which is the marker of interstitial lymphatic involvement due to the spread of malignant lung disease [Figure 1].

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Figure 1:

Chest X-ray posteroanterior view showing left hilar opacity with linear spreading margins and edges typical “Sunray sign.”

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Clinical examination documented

Well-nourished, moderately built, anxious male, no cyanosis or clubbing.

Heart rate – 98/min, Respiratory rate – 24/bpm, blood pressure – 110/60 mmHg.

PsO_2: 96% @ room air.

Respiratory system examination revealed – normal vesicular breathing and no adventitious breath sounds were heard in the bilateral lung field.

Other systemic examinations were normal.

We have performed contrast computed tomography (CT) Thorax and documented a homogeneous round mass with the left mainstem bronchus involvement suggestive of bronchogenic malignancy [Figure 2].

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Figure 2:

High-resolution computed tomography thorax showing mass lesion left lung upper lobe with the left main bronchus infiltration.

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Laboratory workup revealed normal hematological, viral markers, and biochemistry analysis. Tropical workup is negative and sputum examination was inconclusive. We have decided to further investigate with bronchoscopy due to the absence of fever, minimal hemoptysis, negative procalcitonin and sepsis screen, and importantly “Sunray sign” in chest radiograph and mass lesion in the left upper lobe abutting and infiltrating left mainstem bronchus. Fiberoptic video-bronchoscopy documented polypoidal multinodular growth in the left mainstem bronchus causing near-total occlusion of the lumen. Bronchoscopy was unable to negotiate distal growth. Growth was fleshy and bleed on touch and showed a yellowish-white slough overlying it. We have performed endobronchial needle aspiration cytology (EBNA) as the first procedure during bronchoscopy due to the presence of slough overgrowth and chances of negative growth and forceps biopsy as the second technique during bronchoscopy. EBNA cytology documented squamous cell type of lung malignancy. Histopathology confirmed as non-small cell lung cancer most likely as squamous cell lung cancer. We have documented the role of undifferentiated non-small cell lung cancer on histopathology to confirm the exact histopathological type by performing immunohistochemistry for estimated glomerular filtration rate, anaplastic lymphoma kinase, and reactive oxygen species to rule out probable adenocarcinoma and finally squamous cell carcinoma (SCC) is the diagnosis made with negative thyroid transcription factor, and positive CK 5/6 and P63 in samples.

DISCUSSION

SCC of the lung usually arises from the epithelium of central or peripheral airways due to carcinogenesis pathophysiology after exposure to carcinogens in tobacco smoke. Squamous cells are thin and flat cells that are found lining many organs of the human body. Tobacco smoke contains 300 harmful agents and 40 known carcinogens which result in the transformation of mucosal linings of airways into altered squamous cells with keratinization and/or intercellular bridges and these structured cells often exhibit a high degree of mutation frequency.^[1]

CONCLUSION

In the present case report, we have documented constitutional symptoms such as cough, hemopoiesis and shortness of breath with absence of fever with negative sepsis screening panel given clue to work for noninfective cause for Sunray sign. With the interventional pulmonology fibre optic videobronchoscopy technique has given diagnostic clue as lung malignancy. EBNA has been an important bronchoscopy guided method apart from forcep biopsy for confirming the diagnosis.

Key learning points from this case report are

1. “Sunray sign” in chest radiograph is hilar mass or radiopacity with inhomogeneous linear opacities spreading toward peripheries like sunrays which is the marker of interstitial lymphatic involvement due to the malignant spread of disease

2. “Sunray sign” is a direct sign of underlying lung malignancy and is documented in two most common histological types such as squamous or small cell cancer tumors due to their propensity to involve central airways and labeled as central tumors

3. The majority of cases with sunray signs present with hemoptysis which is the marker of central airway tumor with endobronchial involvement

4. Bronchoscopy is the gold standard test to diagnose endobronchial pathology than high-resolution CT thorax. It should be done to rule out the exact cause for the Sunray sign

5. Various bronchoscopy-guided techniques are available and the sequence of techniques usually depends on the choice and expertise of the operator during the procedure. EBNA is underutilized over forceps biopsy in endobronchial lesions due to lack of training, and fear of bronchoscope damage by EBNA during the procedure

6. Forceps biopsy is considered a gold standard test in endobronchial lesions due to the larger sample size and adequacy of specimens for further analysis such as immunohistochemistry. EBNA has overtaken these concepts and becomes the first test during bronchoscopy in endobronchial lesions with superficial necrosis or slough over the lesion, blood clot over the lesion, and or crush artifacts resulting during biopsy samplings, especially with serrated edges forceps during bronchoscopy

7. “Sunray sign” will be documented in squamous cell lung cancer or small cell lung cancer. In search of published literature, this will be our first case in the name of “Sunray sign” in lung malignancy

8. “Sunray sign” is easily picked up during routine chest radiology examinations. Family physicians and general physicians’ training are must for the most common radiological signs of lung malignancy including Sunray signs to prevent delay in diagnosis and have successful treatment outcomes.