Document Type

Conference Proceeding

Publication Date

5-2026

Abstract

Clinical History A 68-year-old male with a history of left tonsillar squamous cell carcinoma treated 5 months ago and reportedly negative recent PET and CT scans of the neck and body with eye pain with possible but uncertain remote history of trauma was sent in for imaging of the orbits. The patient has a feeding tube and was recently hospitalized and discharged for tube obstruction. Imaging Findings Orbital imaging revealed diffuse signal alterations involving the orbital and scalp fat, and marrow, characterized by low signal intensity on T1WI and high signal intensity on T2WI. In particular on the STIR sequence, there was lack of fat suppression in the orbits and adjoining soft tissues. Postcontrast images of the orbits showed diffuse enhancement of the retrobulbar intra-orbital fat without evidence of a discrete mass initially mimicking diffuse infiltration. Both globes appeared normal in morphology, the optic nerves were intact without compression and the extra-ocular muscles were normal in size. In addition, a left cavernous sinus mass was detected that was new from 6 months earlier head CT. Though the cavernous sinus mass was concerning for neoplastic involvement, the more extensive findings in the fat of the orbits and particularly the bone marrow were favored to represent orbital lipolysis and a sequela of serous atrophy of the bone marrow with a “flip-flop” characteristic appearance. Subsequent discussion confirmed severe malnutrition from the cancer and recent feeding tube issues, with significantly low BMI. Discussion Serous atrophy of the bone marrow (SABM), or gelatinous transformation, is a metabolic response to catabolic stress or chronic illness. It involves depletion of marrow fat, hypoplasia of hematopoietic cells, and deposition of mucopolysaccharide-rich gelatinous material, leading to increased water content and a characteristic MRI pattern of diffuse low T1 and high T2 signal within marrow and adjacent fat-containing tissues. This case demonstrates the characteristic “flip-flop” pattern involving the marrow, scalp, and orbital fat, with diffuse retrobulbar enhancement but no discrete mass. Recognition of SABM is essential, as its diffuse signal abnormalities may mimic infiltrative marrow disorders. Unlike malignant infiltration, which presents with focal enhancement and discrete nodules, SABM shows a homogeneous pattern without focal lesions. Understanding this distinction helps avoid unnecessary biopsies or imaging. Pathophysiologically, SABM reflects advanced fat depletion replaced by water-rich gelatinous material in severe malnutrition or systemic wasting. Orbital findings represent lipid peroxidation of retrobulbar fat, called orbital lipolysis, resulting in diffuse loss of T1 signal and a “pseudo fat-saturated” appearance. Diffuse orbital enhancement likely reflects contrast leakage through compromised capillaries from the same catabolic process. Although uncommon, simultaneous marrow and orbital involvement underscores their shared etiology. Teaching Point Diffuse T1 hypointensity and T2 hyperintensity involving marrow, scalp, and orbital fat with preservation of normal anatomy and absence of focal mass should raise suspicion for serous atrophy of the bone marrow. Recognition of the characteristic “flip-flop” appearance, extending beyond bone marrow to orbital and subcutaneous fat, can prevent misdiagnosis of infiltrative disease and prompt evaluation for underlying systemic or nutritional disorders.

First Page

95

Last Page

96

Comments

American Society of Neuroradiology ASNR26 Conference, May 17-20, 2026, Austin, TX

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