Head and Neck Imaging
Positron Emission Tomography–Computed Tomography Evaluation of Maxillary Rhabdomyosarcoma in an Adult
Regino Cube, MD,1 Yang-En Kao, MD2 and Stephen Yoest, MD3
1. Resident, Department of Radiology; 2. Chief, Department of Nuclear Medicine; 3. Attending Neuroradiologist, Department of Radiology, Madigan Army Medical Center
Abstract
Rhabdomyosarcoma is a rare primary head/neck tumor. This article illustrates the utility of multimodality imaging techniques in a 34-year-old male with metastatic alveolar rhabdomyosarcoma, including an apparently favorable metabolic response to chemotherapy between baseline and early post-treatment positron emission tomography–computed tomography. Clinical and histopathologic features of the disease are also presented.
Keywords
Alveolar rhabdomyosarcoma, magnetic resonance imaging, fluorodeoxyglucose positron emission tomography–computed tomography, myo-D1, Children’s Oncology Group ARST0431 trial
Disclosure: The authors have no conflicts of interest to declare. Acknowledgment: The authors would like to thank Karen Strenge, MD, for her work in providing the histologic images of this case report. Received: April 21, 2011 Accepted: August 5, 2011 Citation: US Radiology, 2011;3:28–31 Correspondence: Regino Cube, MD, Madigan Army Medical Center, 9040 Fitzsimmons Drive, Tacoma, WA 98431. E:
regino.cube@
us.army.mil
Rhabdomyosarcoma is the most common soft-tissue sarcoma in pediatric patients, with less frequent occurrence in young adults. The head/neck is a common site for this tumor with frequent involvement of the orbit, nasal cavity, nasopharynx, and paranasal sinuses. Although imaging features of head/neck rhabdomyosarcoma are non-specific and may resemble an aggressive fungal infection or other malignant neoplasm, histopathologic features are often definitive with characteristic myoid differentiation and immunohistochemical profile. This article presents a rare case of maxillary sinus rhabdomyosarcoma in an adult patient, with demonstration of a favorable metabolic response to multiagent chemotherapy between baseline and early post-treatment fluorodeoxyglucose positron emission tomography–computed tomography (F18-FDG PET-CT).
Case Report
A 34-year-old man presented to the emergency department (ED) with left facial pain, pressure, and nasal congestion of several weeks’ duration. Within a three-month period, the patient had been seen in the ED twice and was treated for presumed sinusitis, demonstrating symptoms refractory to antibiotic treatment. A review of the patient’s medical history was otherwise unremarkable.
Physical examination revealed an obvious left proptosis without abnormality of visual acuity. Extraocular movements were symmetric and intact. His otoscopic examination was unremarkable. Rhinoscopic examination revealed rightward deviation of the nasal septum with obliteration of the left nasal passage by an apparent soft-tissue mass
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beyond the vestibule. Oropharyngeal examination revealed no significant abnormality. No palpable lymph nodes of the neck were identified. Cranial nerve examination revealed hypesthesia in the distribution of the left maxillary nerve. Laboratory examination demonstrated a mild hypercarbia and lymphocytosis.
The patient underwent non-contrast CT of the sinuses, which revealed a large soft-tissue mass centered in the left maxillary sinus with significant osseous erosion into the hard palate, left orbit, and left nasal cavity, as well as displacement of left maxillary soft tissues (see Figure 1). Inflammatory changes were also seen in the ipsilateral frontal and sphenoid sinuses. Contrast-enhanced magnetic resonance imaging (MRI) of the sinuses demonstrated a heterogeneously enhancing cystic mass that was primarily T1 isointense to gray matter (see Figure 2). Additional MRI findings included anterior extension through the left infraorbital foramen and some erosion of the cribriform plate, without definite invasion into the anterior cranial fossa. Given the aggressive appearance of the lesion, differential considerations included neoplastic etiologies such as inverting papilloma or squamous cell carcinoma, or possibly an invasive fungal sinusitis. Pathology revealed a malignant small round blue cell tumor with an immunohistochemical profile consistent with rhabdomyosarcoma (alveolar type). Histopathologically, the tumor demonstrated a growth pattern of the solid variant, with periodic acid Schiff positivity of the neoplastic cells. The tumor cells showed positive immunoreactivity for desmin and myo-D1, with a nuclear staining pattern (see Figure 3).
© TOUCH BRIEFINGS 2011
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