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Title

Atypical inflammatory myofibroblastic pseudotumor of the etmoidal sinus extending into the orbit

Purpose	To report a case of an atypical inflammatory pseudotumor of the paranasal sinuses with bony invasion extending into the orbit .
Methods	Case-report.
Results	A 71-year old man presented with slowly progressive painless diplopia followed by unilateral proptosis of the left eye with a slight edema of the upper eyelid. Visual acuity was 0.4 with a relative afferent pupillary defect . Abduction and depression of the left eye were limited. Imaging showed an orbital tumor around the obliquus superior with lateral displacement, possible infiltration of the superior and medial rectus, involvement of fossa pterygopalatinum , sinus etmoidalis, sphenoidalis and maxillaris , intracranial extension through the fissura orbitalis superior, bone erosion and sclerotic bone reaction. Endoscopic ethmoïdal, maxillary and orbital biopsies discovered a inflammatory myofibroblastic tumor. Blood parameters showed eosinophily. ANCA and CRP were negative. Discussion: In the literature three cases of orbital myofibroblastic tumors have been described but never with bone invasion. Only a few sinus inflammatory pseudotumors with bony erosion have been reported. Central nervous system myofibroblastic tumors give a dura based mass-forming an en plaque pattern. Two cases with orbital involvement have been described.
Conclusion	This eroding sino-orbital inflammatory myofibroblastic tumor is a new finding mimicking a malignant tumor.

Author 1

Last name	LAUWERS
Initials	N
Department	Antwerp University Hospital, Department of Ophthalmology
City	Edegem

Author 2

Last name	De Groot
Initials	V
Department	Antwerp University Hospital, Department of Ophthalmology
City	Edegem

Author 3

Last name	Leysen
Initials	I
Department	Antwerp University Hospital, Department of Ophthalmology
City	Edegem

Author 4

Last name	Claes
Initials	J
Department	Antwerp University Hospital
City	Edegem

Author 5

Last name	De Keizer
Initials	R
Department	Antwerp University Hospital, Department of Ophthalmology
City	Edegem