Brain Pathology Case of the Month - November 2016

Contributed by Reena Baweja1, Kesava Reddy1, Anthony Whitton2, John Provias3, Boleslaw Lach3
Departments of 1Neurosurgery, 2Oncology, and 3Neuropathology of Hamilton General Hospital, McMaster University, Hamilton, Canada


This 65 year old female who was diagnosed with a right CP angle tumor after an MRI was done to investigate facial pain in 1999. In 2006, her pain became quite severe and she developed numbness in all three divisions of the trigeminal nerve along with decreased corneal reflex and facial paresis on the right side. The lesion was partially resected at the time by right retrolabyrinthine approach with pre and post sigmoid craniectomy. The patient recovered uneventfully except for wound infection, which required debridement. In 2012, she presented with left sided weakness and gait instability. MRI with gadolinium showed a recurrent hypointense lesion with rim enhancement as well as an enhancing nodule at the tentorial incisura on the right side (Figure 1a). A subtemporal approach was undertaken with subtotal resection of tumor that encircled the right posterior cerebral artery. Postoperatively, she received stereotactic radiosurgery with Cyberknife for a total of 2500 cGy. In spite of this, her lesion progressed. She continued to worsen neurologically and an Ommaya reservoir was inserted for aspiration of the cystic portion of the lesion. She has since begun a radiation boost to the area of 54 Gy in thirty fractions.


The specimen from the surgery in 2006 consisted of multiple grey-white feathery portions of tissue measuring 0.1 to 1.0 cm in diameter. Microscopic examination revealed fragments of thin layers of connective tissue capsule lined by squamous epithelium, and filled with keratin flakes (Figure 1b). The specimen from the second surgery in 2012 consisted of multiple fragments of firm tan-white tissue measuring 2.0 x 1.5 x 0.3 cm. Microscopic examination revealed highly anaplastic keratin positive squamous epithelium infiltrating underlying connective tissue and brain (Figures 1c and 1d). The epithelium showed a marked degree of nuclear hyperchromasia and atypia with a very high proliferation rate, which was confirmed by MIB-1 (Figure 1e). Immunostaining for melanin and p53 was negative. What is your diagnosis?


International Society of Neuropathology