Daily Radiology Case

Explanation

The MRI demonstrates a heterogeneous solid mass centered at the olfactory recess with cribriform plate transgression, intracranial extension, and peritumoral marginal cysts at the tumor–brain interface, diagnostic of olfactory neuroblastoma (esthesioneuroblastoma). This rare neuroectodermal tumor arises from the olfactory neuroepithelium of the upper nasal cavity and is histologically characterized by Homer-Wright pseudorosettes within a fibrillar neuropil background, graded I–IV by the Hyams system. The dumbbell-shaped growth pattern straddling the cribriform plate with intracranial marginal cysts is highly suggestive though not pathognomonic, as MRI signal characteristics overlap with other sinonasal malignancies. Management is multimodal with craniofacial resection and adjuvant radiotherapy, with Kadish staging and Hyams grade serving as the principal prognostic determinants.

Source: Mora Diez C, Olfactory neuroblastoma. Case study, Radiopaedia.org (Accessed on 28 Apr 2026) https://doi.org/10.53347/rID-233287

Hints

• A 35-year-old male presents with a two-month history of progressive left eye pain and proptosis, accompanied by gradual nasal obstruction and intermittent epistaxis.
• On physical examination, there is non-axial proptosis of the left globe with restricted upgaze, and anterior rhinoscopy reveals a fleshy, vascular polypoid mass occupying the superior nasal cavity. Cranial nerve testing demonstrates anosmia on the affected side.
• Further evaluation shows no cervical lymphadenopathy or distant metastases, and biopsy reveals sheets of medium-sized cells with regular nuclei, fine "salt-and-pepper" chromatin, an eosinophilic fibrillar background, and Homer-Wright pseudorosettes (Hyams grade 2).
• MRI demonstrates a large, heterogeneous, solid tumor centered in the superior nasal cavity at the olfactory recess, with low ADC values reflecting high cellularity, eroding the ethmoid air cells and destroying the lamina papyracea.
• The mass invades the fat planes of the superomedial orbit and extends superiorly through the cribriform plate into the anterior cranial fossa, exerting significant mass effect on the frontobasal brain parenchyma.
• A relatively characteristic finding on T2-weighted imaging is the presence of peritumoral cysts at the tumor–brain interface, considered highly suggestive of this neuroectodermal malignancy arising from specialized sensory epithelium of the upper nasal vault.