Intravascular metastatic melanoma: A difficult diagnosis

BRIEF REPORT

Intravascular metastatic melanoma: A difficult diagnosis

Samer Ghattas,1 Julie Howle,2 Wei Wang,3 Richard Kefford4 and Simon Gruenewald1

1Department of Nuclear Medicine, PET and Ultrasound, 2Surgery, 3Radiation Oncology and 4MedicalOncology, Westmead Hospital, Sydney, New South Wales, Australia

ABSTRACT

Melanoma is a common cancer with the potential forwidespread metastasis; however intravascular metas-tasis is extremely rare. We report an unusual case ofa patient with metastatic melanoma in whom 18F-fluorodeoxyglucose positron emission tomography-computed tomography (FDG PET-CT) demonstratedan intravascular melanoma metastasis in the superiorvena cava (SVC), successfully treated with externalbeam radiotherapy. To our knowledge, this is the firstreported case where FDG PET-CT was used to makethis diagnosis.

Key words: melanoma, positron-emission tomog-raphy, radiotherapy, vena cava, superior, venoustrombosis.

INTRODUCTION

Melanoma is a common malignancy with a propensityfor widespread metastasis. 18F-fluorodeoxyglucose positronemission tomography-computed tomography (FDG PET-CT) is a validated and sensitive modality for detecting softtissue, lymph node and visceral metastases in melanoma,and it is useful in identifying unusual metastatic sites.1,2

A patient is presented in whom FDG PET-CT revealedan intravascular metastasis not discovered on anatomicimaging.

CASE HISTORY

A 72 year-old man presented with a subcutaneous left axil-lary mass 2 years after a wide local excision and negativesentinel lymph node biopsy as treatment for a left shoulder

melanoma, Breslow thickness 2.4 mm. Staging CT demon-strated a 3 cm left axillary mass and discrete pulmonarymasses in the left apex (1.2 cm), left upper lobe (1.5 cm) andright upper zone (0.5 cm). The axillary mass was excisedand confirmed as a BRAF-wild type metastatic melanoma.

The patient was subsequently referred for a staging FDGPET-CT, demonstrating hypermetabolism in all three lunglesions and an unexpected hypermetabolic focus (standard-ised uptake value 4.4) in the lower SVC, near the rightatrium, consistent with tumour thrombus (Fig. 1).

On retrospective review of the initial diagnostic CT scansan area of heterogeneous radiodensity was seen in the SVC-right atrium junction (Fig. 2). It was not reported, however,as it may have been regarded as a mixing artefact.

The patient proceeded to a CT venogram, confirminga non-occlusive SVC thrombus (Fig. 3). He commencedwarfarin and underwent chemotherapy (ipilimumab/dacarbazine) and external beam mediastinal radiotherapy(20 Gy in 5 fractions, using parallel opposed fields). A repeatCT venogram 3 months later showed a near-complete reso-lution of the thrombus (Fig. 4).

DISCUSSION

Although in transit endolymphatic metastases of malignantmelanoma are common, distant intravascular metastaseshave rarely been reported. Blanco and colleagues3 reporteda case of SVC obstruction due to intravascular metastaticmelanoma, Saint-Cyr and colleagues4 reported intravascu-lar metastatic melanoma in the saphenous vein, mimickingthrombophlebitis and Harris and colleagues5 documented acase of acute aortic occlusion secondary to a malignantmelanoma tumour embolus.

To our knowledge this is the first reported case in whichFDG PET-CT diagnosed intravascular SVC melanomametastasis. In this case, the moderate dose of palliativeradiotherapy effectively treated the intravascular meta-stasis. Progress CT 3 months post-radiotherapy showed anear-complete resolution of the intravascular metastasis.

Correspondence: Dr Samer Ghattas, Westmead Hospital,Hawkesbury Road, Westmead, Sydney, NSW 2145, Australia. Email:s.ghattas1@gmail.com

Samer Ghattas, MBBS (Hons). Julie Howle, FRACS. Wei Wang,FRANZCR. Richard Kefford, FRACP. Simon Gruenewald, FRACP.

Conflicts of interest: none.Submitted 18 June 2012; accepted 9 November 2012.

Abbreviations:

FDG PET-CT 18F-fluorodeoxyglucose positron emissiontomography-computed tomography

SVC superior vena cava

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Australasian Journal of Dermatology (2013) 54, 141–143 doi: 10.1111/ajd.12033

© 2013 The AuthorsAustralasian Journal of Dermatology © 2013 The Australasian College of Dermatologists

However the pulmonary metastases, which were not irra-diated, had progressed in size.

CONCLUSION

FDG PET-CT is a useful investigative tool in patients withmetastatic melanoma, enabling the diagnosis of metastasesnot easily appreciated on conventional CT. Radiotherapymay offer a successful treatment for such metastases.

REFERENCES

1. Krug B, Crott R, Lonneux M et al. Role of PET in the initialstaging of cutaneous malignant melanoma: systematic review.Radiology 2008; 249: 836–44.

Figure 1 18F-fluorodeoxyglucose positron emission tomography-computed tomography. Hypermetabolic focus demonstrated at the superiorvena cava-right atrium junction (arrow). Metastatic pulmonary nodule also seen (arrowhead).

Figure 2 Arterial-phase i.v.-contrast-enhanced computed tomog-raphy. Area of heterogeneous radiodensity (arrow) evident in thesuperior vena cava but was probably regarded as a mixing artefact,and therefore not noted in the radiologist’s report.

Figure 3 Computed tomography venogram. Rounded filling defect(arrow) in the lower superior vena cava substantiates the diagnosisof intravascular melanoma metastasis.

Figure 4 Computed tomography venogram (post-radiotherapy).Thrombus (arrow) has almost resolved. Note progressive pulmo-nary metastasis (arrowhead).

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2. Ozulker T, Ozulker F, Cicin I et al. A case of malignantmelanoma with cardiac and gallbladder metastases detectedby FDG PET-CT. Clin. Nucl. Med. 2009; 34: 948–9.

3. Blanco P, Ly S, Beylot Barry M et al. Surgical treatment of anendovascular metastatic melanoma of the superior vena cava.Dermatology 1999; 199: 156–7.

4. Saint-Cyr I, Boisseau-Garsaud AM, Pont F et al. Intravascularmetastatic melanoma of the vena saphena magna. Int. J. Der-matol. 2004; 43: 590–2.

5. Harris RW, Andros G, Dulawa LB et al. Malignant melanomaembolus as a cause of acute aortic occlusion: report of a case.J. Vasc. Surg. 1986; 3: 550–3.

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© 2013 The AuthorsAustralasian Journal of Dermatology © 2013 The Australasian College of Dermatologists