Demonstration of Multiple Metastatic Sites by Positron Emission Tomography/Computed Tomography in a Rare Case of Epithelioid Angiosarcoma of the Scalp

Abstract

Epithelioid angiosarcoma is a rare subtype of angiosarcoma, with metastases occurring in more than 50% of cases and the lung is the most organ which is involved. Whole-body fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) has demonstrated its clinical utility in the early detection of metastases in angiosarcoma. It is helpful to differentiate between benign lesions with low FDG uptake as compared to malignancies with high FDG avidity. Here, we present a rare case of a young man with epithelioid angiosarcoma, in which FDG PET/CT has demonstrated metastatic sites (especially lung metastases).

A 24-year-old man presented with multiple painless scalp swellings for the past 4 months. These were smooth and nonmobile. The patient complained of pain over right occipital swelling. No palpable cervical or axillary lymph nodes were found on examination. Magnetic resonance imaging (MRI) brain was performed to assess the swelling and revealed well-defined, encapsulated, iso-intense on T1, and intermediate-to-hyperintense on T2 lesions in the scalp over the right occipital region. Another ring-enhancing lesion with perilesional edema was seen in the left parieto-occipital region [Figure 1a and b]. The patient underwent fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for detection of the primary and overall assessment of the disease, which showed [Figure 2a-e] metabolically active right parieto-occipital scalp lesion, ground-glass lung opacities with low-grade metabolism, and ring enhancing brain lesion in the left occipital lobe. Another FDG avid soft-tissue lesion was noted in the left upper back. Multiple bilateral lung nodules with surrounding ground glassing opacities were noted (CT halo sign), which is a classic finding for hemorrhagic lung metastases. Since the ground-glass opacities raised suspicion of hemorrhagic metastases, a biopsy was performed to confirm the same. The histopathological report turned out to be an epithelioid subtype of angiosarcoma. On immunohistochemical examination, the tumor cells were positive for CD 31, AE1/AE3, and EMA (epithelial membrane antigen) and negative for CD 34, S100P, SMA, and desmin. INI1/SMARCB1 is retained in tumor cells. The patient was started on metronomic chemotherapy.

Figure 1: (a) A well-defined enhancing lesion seen in the scalp in the right occipital region on post contrast T1 FSPGR sequence (arrow). Another enhancing lesion was seen in the left parieto-occipital region of the brain (arrowhead). (b) T2W images show a heterogeneous appearing scalp lesion (arrow). Parieto-occipital lobe brain lesion appears hyperintense with surrounding edema (arrowhead). FSPGR - fast spoiled gradient-echo, T2W: T2 weighted

Figure 2: MIP (a) (black arrow), fused (b), and axial (c) (arrows) images shows FDG avid scalp lesion in the right occipital region. Axial fused PET/CT images (d) and CT image (e) show bilateral ground glass opacities surrounding the soft-tissue nodule which is classic CT sign (Halo sign) for hemorrhagic lung metastases (arrows). Sagittal fused PET/CT (f) and sagittal CT (g) (arrows) images showed left parieto-occipital brain lesion, PET/CT: Positron emission tomography/computed tomography, FDG: Fluorodeoxyglucose, MIP: Maximum Intensity Projectiion

Discussion

Angiosarcoma is an aggressive, malignant endothelial cell tumor of lymphatic or vascular origin and represents <1% of all soft-tissue sarcoma.[¹] A unique and rare morphologic subtype of angiosarcoma, in which the malignant cells have a predominantly epithelioid appearance is called epithelioid angiosarcoma. It has a male predilection with the highest incidence in the seventh decade of life. These tumors have aggressive nature with more than 50% of cases have <5-year survival.[²] There are reported cases of epithelioid angiosarcoma involving the thyroid,[³] ovary,[⁴] bone,[⁵] and deep soft tissue.[⁶] Metastases occur in more than 50% of patients with epithelioid angiosarcoma and the lung is the primary organ involved. Patients with lung metastases often present with respiratory-associated symptoms such as hemoptysis, cough, and dyspnea.[⁷]

MRI features of tumor include intermediate T1 signal intensity with possible regions of hyperintensity suggestive of hemorrhage with high T2 signal intensity. The most important finding is the presence of high-flow serpentine vessels (low-signal intensity on both T1- and T2-weighted images) in an otherwise solid nonspecific soft-tissue mass. Low flow vessels, however, may show hyperintensity on T2-weighted images. Angiosarcoma demonstrates enhancement after intravenous contrast administration and may show nonenhancing areas reflecting tumor necrosis. Although these imaging features are relatively nonspecific, they indicate malignancy and should prompt biopsy for further characterization.[^8,9] FDG-PET/CT provides important details that can be used in the diagnosis, staging, restaging, treatment response monitoring, and prognostication of STSs (soft-tissue sarcomas). FDG PET/CT has provided some reliability in the early detection of distant metastases, staging, and its prognostication of angiosarcoma.[¹⁰] Benign vascular lesions, such as hemangiomas and hemangioendothelioma, demonstrate significantly lower FDG avidity compared with angiosarcoma, allowing distinguishability.[¹¹]

There are reported cases of the demonstration of metastases in cardiac angiosarcoma by FDG PET.[¹²] In this case, whole-body PET/CT scan has been helpful to demonstrate hemorrhagic lung metastases and other sites of disease involvement, thus providing the complete assessment of disease in this rare malignancy.

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Financial support and sponsorship

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Conflicts of interest

There are no conflicts of interest.