A Case of Metastatic Sarcomatoid Squamous Cell Carcinoma Presenting as Left Ventricular Masses

Description of Clinical Presentation: A 61 year old male, with a background of gamma heavy chain disease on monthly intravenous immunoglobulin and multiple past haematological malignancies, presented initially with relapsed Hodgkin lymphoma and was treated with brentuximab vedotin. During treatment, he developed concurrent locally advanced cutaneous squamous cell carcinoma (SCC) of the cheek. This was resected with adjuvant radiotherapy but subsequently found to have metastasised to the left trapezius and right retropectoral regions. A follow-up FDG-PET showed interval increase in size of these masses, with CT whole body showing additionally a left ventricular (LV) apex mass. Cardiac magnetic resonance imaging (CMR) demonstrated two irregular LV cardiac masses: an apical mass, covered in clot and protruding into the LV cavity, and a basal lateral, epicardial infiltrative myocardial mass. A surgical debulking of the apical mass with biopsy of the epicardial mass was performed, with the apical mass identified as metastatic sarcomatoid squamous cell carcinoma (SSCC), and the epicardial mass showing fibrovascular stroma on histopathology. Palliative intent cemiplimab, a monoclonal antibody against programmed cell death-1 receptor was started. A repeat CMR, 2 months post-surgery, demonstrated a recurrence of the apical LV mass, with interval reduction in size of the epicardial mass.

Diagnostic Techniques and Their Most Important Findings: 1.5T CMRs were performed with standard steady-state free possession cine imaging for morphology and volumetric analysis. In addition, T1-weighted, T2-weighted spin echo fat suppressed (FS SE), 1^st pass perfusion, early (EGE) and late gadolinium (LGE) imaging sequences were performed. Apical mass was pedunculated and attached to the distal inferior wall, measuring 49mm in length, whereas epicardial mass measured 48mm in length. Both masses were iso/mildly hyperintense on T1-weighted image, hyperintense on T2 FS SE. On 1^st pass perfusion, apical mass demonstrated no obvious perfusion, and epicardial mass showed patchy areas of perfusion. Both masses are hypointense on EGE with heterogenous appearances on LGE. Similar tissue characteristics of both masses were demonstrated on repeat CMR.

Learning Points from this Case: Cardiac metastases are found in 6-20% of autopsies in patients with malignant neoplasm [1]. Most commonly, they arise from primary malignancies of melanoma, lymphoma, leukaemia, and solid organ cancers of lung and breast [2, 3]. Cutaneous SCC rarely metastasises to the heart. SSCC, a biphasic tumour composed of malignant epithelial and spindle cells, is a very rare variant of SCC. To date, there are no case reports of metastatic SSCC of the heart. We described this rare presentation, alongside diagnostic uncertainty with concurrent malignancies, and highlighted the aggressive nature of this tumour type with frequent recurrence and poor prognosis. CMR provided detailed tissue characterisation and aided in the diagnosis, with tissue characteristics of the masses mirroring those classically described for undifferentiated sarcoma [4].

Figure 1: T1-weighted imaging in horizontal long-axis view demonstrating iso/mildly hyperintense left ventricular apical and basal lateral masses
Figure 2: T2-weighted spin echo fat suppressed imaging in horizontal long-axis view demonstrating hyperintense left ventricular apical and basal lateral masses
Figure 3: Late gadolinium acquisition imaging in horizontal long-axis view demonstrating heterogenous appearances of left ventricular apical and basal lateral masses