Case 781 -- A 59-year-old woman with a retroauricular tumor

Contributed by Alejandra Magagna-Poveda1, MD, PhD; Karl J. Frontzek1, MD
     Beata Bode-Lesniewska2, MD; Elisabeth J. Rushing1, MD
1Institute for Neuropathology, 2Institute for Clinical Pathology, University Hospital Zurich, Zurich, Switzerland


A 59-year-old woman presented with an 8-year history of generalized malaise, neck and arm pain and hearing impairment. Six months prior to admission she developed night sweats and a 4 kg weight loss. These symptoms progressed to include headaches, gait instability and the appearance of a painful retroauricular mass. Laboratory analysis showed the following results: haemoglobin, 12.7 g/dl; mean corpuscular volume (MCV), 78.7 fl; thrombocytes count, 483x103/ l; white blood cell count, 15.84x103/ l; neutrophiles count 13.46x103/ l; lymphocytes count, 1.34x103/ l; 4.8% microcytic erythroblasts; sodium, 131 nmol/L. Cranial computed tomography (CT) revealed an osteolytic mass lesion measuring 5 cm in diameter that, extended from the right mastoid to the medial and posterior cerebral fossae. On cranial magnetic resonance imaging (MRI, Figure 1) the 6.8x5.3x4.8cm, poorly circumscribed, extra-axial mass with progressive perifocal edema was noted to extend into the cerebellum, with compression of the IV ventricle and the brainstem. On T1-weighted images, the lesion appeared iso- to hypointense, with solitary intratumoral vessels and haemorrhagic components. T2-weighted images of the mass showed low-signal intensity with inhomogeneous contrast-enhancement. The preoperative differential diagnosis included osteosarcoma, hemangiopericytoma, and metastatic disease. Preoperative fine needle aspiration biopsy (FNA) of the extracranial retroauricular mass was performed. Thorax/abdomen CT performed as part of a metastatic workup did not reveal evidence of other mass lesions. The patient underwent complete surgical resection of the lesion following embolisation.


Grossly, the mass was firm and hemorrhagic, measuring 5.0x4.5x1.5cm. Microscopic examination revealed several patterns (Figure 2) including areas dominated by widely-scattered, plump, ganglion-like cells with prominent nucleoli embedded in a dense, hyalinized matrix (Figures 3 and 4). In other regions, the matrix was loose and contained slender spindle cells. Multifocal collections of chronic inflammatory cells, especially plasma cells, were present (Figures 3 and 5). Additionally, there was evidence of recent and old hemorrhage. Occasional mitotic figures, including atypical forms, and necrosis were identified. The ganglion-like cells stained strongly and diffusely for smooth muscle actin (Figure 6) and occasional cells labeling with desmin (Figure 7). Immunostaining was negative for anaplastic lymphoma kinase-1 (ALK-1), myo-D1, myogenin, cytokeratin, EMA, S-100, and panMela. Fluorescence in situ hybridization (FISH) performed on the direct smears of the FNA did not reveal rearrangement of the ALK-1 gene (Figure 8). Latent membrane protein-1 (LMP-1) and ISH for Epstein-Barr encoded RNAs (EBER) showed no association with an EBV-infection. What is the diagnosis?


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