Illuminating Miliary Sarcoidosis: A Case Report

doi:10.21203/rs.3.rs-4696209/v1

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Case Report

Illuminating Miliary Sarcoidosis: A Case Report

https://doi.org/10.21203/rs.3.rs-4696209/v1

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Background

Sarcoidosis is a multisystem disease characterized by non-caseating granulomas, typically identified by peribronchovascular and perilymphatic nodules on high-resolution computed tomography (HRCT). Miliary sarcoidosis, an atypical presentation involving diffuse pulmonary infiltrates, is rarely reported, occurring in less than 1% of cases.

Case Presentation

We present a case of a 60-year-old Caucasian woman with unexplained weight loss, breathlessness, and cough. Initial chest CT revealed extensive hilar and mediastinal lymphadenopathy with diffuse pulmonary infiltrates, suggesting disseminated malignancy. However, subsequent PET-CT scans showed intense and widespread FDG avidity throughout the lungs and mediastinal nodes, indicative of miliary sarcoidosis. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) confirmed non-caseating granulomas, leading to a diagnosis of sarcoidosis. The patient was treated with oral corticosteroids, resulting in significant clinical and radiological improvement.

Conclusion

This case underscores the importance of recognizing atypical imaging patterns in sarcoidosis, such as miliary distribution, to avoid misdiagnosis and ensure appropriate management. The combination of advanced imaging techniques and minimally invasive biopsy procedures is crucial for accurate diagnosis and effective treatment.

Miliary sarcoidosis

FDG PET-CT

Non-caseating granulomas

Endobronchial Ultrasound -Transbronchial Needle Aspiration

Sarcoidosis is a multisystem disease characterised by non-caseating granulomas. Sarcoidosis is typically identified by the presence of peribronchovascular and perilymphatic nodules on high-resolution computed tomography (HRCT). Although the miliary pattern of sarcoidosis is recognized, it is infrequently detailed in literature (1). Miliary distribution is regarded as an atypical presentation of pulmonary sarcoidosis, occurring in less than 1% of cases (2). We report a rare case of sarcoidosis exhibiting a miliary pattern characterized by diffuse and intense FDG uptake.

A 60-year-old Caucasian woman was referred to a 2-Week Wait Lung cancer clinic due to abnormal chest imaging, breathlessness, unexplained weight loss, malaise, and dry cough. She had skin lesions on her right forearm suspicious for erythema nodosum but had no arthralgia or visual complaints. She had no symptoms suggestive of cardiac involvement. She is a former smoker and denied any known occupational inhalational exposures. Years ago, she was told she was allergic to budgerigars, which she then removed from her environment, and she has had no recent exposure to birds or pets. She had no exotic hobbies and no history of incarceration or travel. She reported no exposure to tuberculosis or family history of pulmonary disease.

During the initial clinic review, her vital signs were stable. The physical examination was unremarkable. Initial lab results showed a normal full blood count, including lymphocytes, serum electrolytes, and liver function tests, while C-reactive protein was mildly elevated at 20 mg/ml. Urine microscopy and serum protein electrophoresis were normal. She had an elevated ACE level of 176 IU/L (normal range: 10–75 IU/L) and low total 25-hydroxy vitamin D at 21 nmol/L. Serum calcium and thyroid function tests were normal. Her electrocardiogram (ECG) was also normal.

A chest X-ray showed bilateral hilar lymphadenopathy and nodular infiltrates. A subsequent CT of the thorax revealed extensive bilateral mediastinal and hilar lymphadenopathy with diffuse nodular infiltrates throughout the lungs in a miliary pattern (Fig. 1).

This was followed by an FDG PET-CT scan, revealing confluent pulmonary infiltrates with diffuse heterogeneity that were FDG avid throughout the lungs. The scan also showed intensely metabolically active enlarged bilateral hilar and mediastinal lymph nodes (Fig. 2).

Her lung function tests at presentation revealed FEV1 2.17 L (81% predicted), FVC 2.43 L (81% predicted), and FEV1/FVC 89%. However, DLCO was not measured due to an error in the machine.

She subsequently underwent EBUS-TBNA with rapid on-site evaluation (ROSE) of mediastinal lymph nodes, which confirmed non-necrotising granulomatous inflammation and no malignant cells (Fig. 3).

Figure 3 (a) An aggregate of epithelioid histiocytes with curved and elongated nuclei, representing non-caseating granulomatous inflammation in a rapid on-site evaluation (ROSE) rapid Giemsa cytology preparation (b) Aggregates of epithelioid histiocytes with curved nuclei surrounded by mixed populations of lymphocytes, representing non-caseating granulomatous inflammation in a rapid on-site evaluation (ROSE) rapid Giemsa cytology preparation (c) An aggregate of epithelioid histocytes with curved and elongated nuclei representing non-caseating granulomatous inflammation in a Papanicolaou (PAP) cytology preparation.

A sample sent to microbiology was negative for mycobacterial culture with no acid-fast bacilli (AFB). After discussing her case images and biopsy results in our thoracic multidisciplinary team meeting, a formal diagnosis of sarcoidosis was made. She was started on oral prednisolone and has shown remarkable improvement in clinical symptoms and follow-up chest X-rays with corticosteroid therapy alone (Fig. 4).

Sarcoidosis is a multisystem disease characterized by well-formed non-caseating granulomas that can involve any organ, most commonly the lungs (3, 4). Classical manifestations include bilateral hilar and right paratracheal lymphadenopathy, though isolated bilateral hilar lymphadenopathy is more common.

Pulmonary sarcoidosis is classified into five stages on a chest X-ray (5, 6) (Table 1 ).

Stage	Features	% at presentation
0	No abnormality	5 to 15
I	Hilar Lymphadenopathy only	45 to 65
II	adenopathy and abnormal lung parenchyma	30 to 40
III	Abnormal lung parenchyma only	10 to 15
IV	Fibrotic changes	5

Abnormalities in the lung parenchyma are primarily observed in the upper and middle lung fields. Micronodules, defined as nodules less than 1 cm in diameter, can be categorized based on their distribution in the lung as perilymphatic, centrilobular, or random. Miliary nodules exhibit a random distribution and can be found near pleural surfaces, small vessels, and interlobular septa, but they do not have a consistent or predominant association with any of these structures (1, 7)

The miliary distribution in sarcoidosis is considered atypical, occurring in less than 1% of cases (2). The diagnosis of sarcoidosis is based on a combination of clinical, radiological, histopathological, cytopathological, and laboratory findings (8). Atypical imaging findings can complicate diagnosis and management due to overlap with other conditions such as disseminated malignancy, tuberculosis, histoplasmosis, and pneumoconiosis.

While FDG PET-CT is not typically part of the initial diagnostic workup for sarcoidosis, it can assess disease activity and distribution in complex cases (9). Diffuse and intense FDG uptake across lymphatic and pulmonary regions, as seen in this case, should prompt consideration of miliary sarcoidosis. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is an appropriate primary diagnostic approach for sarcoidosis, often combined with bronchoalveolar lavage (BAL) or transbronchial biopsy (10). This method can differentiate between tuberculosis, malignancy, and sarcoidosis. In our patient, the EBUS-TBNA biopsy sample showed typical naked non-caseating granulomas of sarcoidosis, with no malignant cells or caseating granulomas with coagulation necrosis, which are commonly seen in tuberculosis. Distinguishing between these aetiologies is crucial to guide appropriate treatment.

Miliary sarcoidosis is an exceptionally rare radiographic pattern and is typically considered a diagnosis of exclusion. Accurate recognition of this pattern is crucial as it facilitates the prompt diagnosis of sarcoidosis while ruling out other conditions. This differentiation is essential for initiating appropriate and timely treatment, ensuring better patient outcomes. Radiological expertise in identifying these patterns can significantly streamline the diagnostic process and improve clinical management.

FDG =Fluorodeoxyglucose, PET-CT =Positron Emission Tomography-Computed Tomography, EBUS=Endobronchial Ultrasound, TBNA=Transbronchial Needle Aspiration

Acknowledgements

The authors thank the patient for her invaluable cooperation and willingness to share her case, which has significantly contributed to this report.

Authors’ contributions

Dr. KKS and Dr. PA made equal contributions to this work, encompassing data collection, manuscript drafting, and literature review. Dr. SC, Dr. MB, and Dr. PA were involved in patient management. Dr. SC additionally contributed to the clinical treatment and provided critical revisions to the manuscript. Dr. NH contributed by compiling the images used in the case report. All authors reviewed and approved the final version of the manuscript.

Funding

No funding or grant were involved in supporting this work.

Availability of data and materials

The data used in this case report are available from the corresponding author upon reasonable request.

Ethical approval and consent to participate

Not applicable.

Consent for publication

Written informed consent was obtained from the patient for publication of identifying images, clinical or other personal details of this case report.

Competing interests

Authors have no competing interests to declare

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No competing interests reported.

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Editorial decision: Revision requested
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You are reading this latest preprint version

Illuminating Miliary Sarcoidosis: A Case Report

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Version 1

Abstract

Background

Case Presentation

Conclusion

Figures

Background

Case presentation

Discussion

Conclusion

Abbreviations

Declarations

References

Additional Declarations

Status:

Version 1