August 2023 Medical Image of the Month: Cannonball Metastases from Metastatic Melanoma

Figure 1. Upright PA chest radiograph (A) demonstrates innumerable rounded nodules with a slight lower lung predilection. Coronal reconstruction from a subsequent chest CT with contrast (B) confirms innumerable round, solid and non-calcified pulmonary nodules most consistent with a “cannonball” pattern of pulmonary metastatic disease.

Figure 2. Axial susceptibility-weighted (A) and pre-contrast T1-weighted (B) images from a brain MRI centered on one (of many) intracranial lesions. This lesion in the posterior right cerebral hemisphere demonstrates a large amount of surrounding susceptibility artifact (A) consistent with blood product, indicating a hemorrhagic metastasis, common in metastatic melanoma which can be very vascular in nature.  There is elevated T1 signal surrounding the lesion (B), also consistent with hemorrhage. There is T1 signal in the center of the lesion as well (arrow), which could represent hemorrhage but could also represent melanin, which is T1 bright and can suggest the primary tumor histology (melanoma).

A 48-year-old man with a significant smoking history presented with progressive dyspnea, a mildly productive cough with brown-tinged sputum, headache, weight loss, and progressive back pain over a period of 8 weeks. The patient had no known history of lung conditions. As part of their initial evaluation, the patient received a frontal CXR and was found to have innumerable rounded pulmonary nodules throughout the lungs, which were consistent with a “cannonball” pattern of pulmonary metastatic disease (Figure 1A). A subsequent CT confirmed innumerable pulmonary metastases (Figure 1B). An MRI of the brain and spine revealed hemorrhagic brain metastases (Figure 2), spinal metastases, and bone metastases. A biopsy of a lesion in the left iliac bone confirmed the diagnosis of metastatic melanoma.

This case highlights the so-called “cannonball” pattern of pulmonary metastatic disease with innumerable round nodules throughout the lungs with a slight lower lung predilection, consistent with a hematogenous spread of disease to the lungs. Classically, this pattern consists of numerous well-circumscribed relatively large lesions in the lungs with a pattern resembling multiple small "cannonballs". The distribution of nodules is random, and the factors that distinguish a cannonball pattern from a miliary pattern of pulmonary metastatic disease are that cannonball metastases are larger and less numerous compared to a miliary pattern of pulmonary metastatic disease (1,2). Although cannonball pattern of pulmonary metastatic disease is classically described in the setting of metastatic renal cell carcinoma, prostate cancer, choriocarcinoma, and sarcoma, it has been reported for a variety of other primary cancers, including melanoma. Similar cases of late-stage metastatic melanoma presenting as widely metastatic disease of unknown origin has also been reported (3).

Melanoma spreads to the lungs through hematogenous dissemination, resulting in the cannonball (or miliary) lesions observed on imaging. Specifically, when these lesions are small and distributed throughout the lung, they commonly indicate metastatic melanoma. While this classical presentation can be pathognomonic, it is important to consider other potential diagnoses, including malignancy, infectious diseases, and rheumatologic conditions. Malignant causes encompass metastatic colorectal cancer, breast cancer, renal cell carcinoma, choriocarcinoma, prostate carcinoma, and adrenal carcinoma. Additionally, non-cancerous causes include infectious etiologies such as septic emboli, coccidiomycosis, histoplasmosis, miliary tuberculosis, and nocardiosis. It is also important to note that rheumatologic conditions like granulomatosis with polyangiitis (Wegener's granulomatosis) can present with the cannonball sign; however, they typically involve both the upper and lower lungs. In this case, the lesions were determined to be due to metastatic melanoma, which had spread to the lungs via hematogenous dissemination.

For this patient, an oncologist was consulted, who recommended that the patient undergo treatment with ipilimumab and nivolumab. The response rate for this treatment regimen generally exceeds 50%, and more than 50% of individuals continue to survive after 5 years. Frequently, when extensive metastases are observed on imaging, healthcare providers often assume a limited life expectancy and tend to lean towards discussions of hospice care. However, it is important to keep in mind that even in cases of extensive metastatic disease, many cancers can be effectively treated with novel and highly effective immunologic anticancer medications.

Andrew Barsoum MD, Mueez Hussain MD, Ranjit Sivanandham MD, and Sina Bagheri MD.

Southwest Healthcare System

Murrieta, California 

References

1. Ammannagari N, Polu V. 'Cannon ball' pulmonary metastases. BMJ Case Rep. 2013 Jan 8;2013:bcr2012008158. [CrossRef][PubMed]
2. Andreu J, Mauleón S, Pallisa E, Majó J, Martinez-Rodriguez M, Cáceres J. Miliary lung disease revisited. Curr Probl Diagn Radiol. 2002 Sep-Oct;31(5):189-97. [PubMed]
3. Lowe A, Bray JJH. Late-stage melanoma presenting with cannonball metastases. BMJ Case Rep. 2020 Dec 12;13(12):e237969. [CrossRef][PubMed]

Cite as: Barsoum A, Hussain M, Sivanandham R, Bagheri S. August 2023 Medical Image of the Month: Cannonball Metastases from Metastatic Melanoma. Southwest J Pulm Crit Care Sleep. 2023;27(2):23-25. doi: https://doi.org/10.13175/swjpccs025-23 PDF

August 2023 Imaging Case of the Month: Chew Your Food Carefully

Michael B Gotway MD¹ and Yasmeen M Butt MD²

¹Departments of Radiology and ²Laboratory Medicine, Division of Anatomic Pathology

Mayo Clinic-Arizona

Scottsdale, Arizona USA

History of Present Illness

A 50-year-old woman presents with a history of chronic dyspnea and cough, becoming particularly problematic following COVID-19 infection 4 months prior to presentation. While she did experience significant periodic oxygen desaturations during her COVID-19 infection, she was not hospitalized for this illness. The patient also reported wheezing in the previous few weeks. 

Past Medical History, Family History and Social History

The patient’s past medical history was also notable for gastroesophageal reflux disease as well as both Coombs positive and iron deficiency anemia. She reports a history of asthma, well controlled with inhaler use.

The patient’s past surgical history included adenoidectomy, cholecystectomy, and gastric laparoscopic band placement.

Her medications included prednisone (20 mg daily), dextroamphetamine-amphetamine, furosemide, omeprazole, fluoxetine, zolpidem (Ambien), daily Bactrim, occasional Loratadine (Claritin). She also utilized an albuterol inhaler and Fluticasone-based (both Flonase and Breo Ellipta) inhalers.

The patient is a former smoker, ½ pack-per day for 26 years, having quit 11 years prior to presentation. She also reported a history of vaping (agent inhaled unclear) for 8 years, quitting 3 years earlier. She has no known allergies. She drinks alcohol socially and denied illicit drug use.

Physical Examination

The patient’s physical examination showed her temperature to be 99°F with normal pulse and respiratory rate but her blood pressure elevated at 160/90 mmHg. She was obese (263 lbs., BMI= 41). Bilateral basal rales were noted at her examination, but no other abnormal physical examination findings were detected.

Laboratory Evaluation

The patient’s room air pulse oximetry was 85%. A complete blood count showed an upper normal white blood cell count at 1.9 x10⁹/L (normal, 4.5 – 11 x10⁹/L). Her hemoglobin and hematocrit values were 10.7 gm/dL (normal, 12 – 16 gm/dL) and 37.1% (normal, 36 – 46%). The patient’s serum chemistries and liver function studies were entirely normal. The patient had an elevated anti-nuclear antibody titer at 1:320. An echocardiogram noted diastolic dysfunction but normal left ventricular contractility.

Frontal chest radiography (Figure 1) was performed.

Figure 1. Frontal chest radiography.

Which of the following statements regarding this chest radiograph is accurate? (Click on the correct answer to be directed to the second of 11 pages)

1. Frontal chest radiography shows normal findings
2. Frontal chest radiography shows marked cardiomegaly
3. Frontal chest radiography shows mediastinal lymphadenopathy
4. Frontal chest radiography shows pleural effusion
5. Frontal chest radiography shows multifocal peribronchial consolidation

Cite as: Gotway MB, Butt YM. August 2023 Imaging Case of the Month: Chew Your Food Carefully. Southwest J Pulm Crit Care Sleep. 2023;27(2):15-22. doi: https://doi.org/10.13175/swjpccs034-23 PDF