This document presents several unknown medical cases involving imaging findings. It discusses cases of a 40-year-old woman with back pain and possible sarcoidosis, a 52-year-old man with a palpable lump evaluated with CT and PET/CT showing a rare hibernoma tumor, and a 75-year-old woman with osteoporosis and an atypical femoral fracture potentially related to long-term bisphosphonate use. It also briefly summarizes a case of serous atrophy in a 20-year-old woman with ankle pain.

1. Panel of unknown cases
Miriam A. Bredella, MD
Associate Professor of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA

2. 40 y/o woman with back pain
T1
STIR
FS T1 + C

3. 40 y/o woman with back pain
STIR
FS T1 + C

4. 40 y/o woman with back pain
STIR
FS T1 + C

5. 40 y/o woman with back pain

6. 40 y/o woman with back pain

7. 40 y/o woman with back pain

8. •Bone involvement rare
•Bone involvement of axial skeleton often asymptomatic
•MRI: intramedullary lesions
–round large, confluent, irregular, patchy diffuse, ± enhancement
•Lesions may involute following treatment
•DD: metastases
Sarcoid

9. 52 y/o man with palpable lump
T1

10. 52 y/o man with palpable lump
CT
FDG PET
fused PET/CT

11. •Rare benign neoplasm
•Composed of brown fat
•Increased vascularity
•↑ FDG uptake
•Adults, mean age 38 y (range 2-75 y)
•Thigh > shoulder > back > neck > chest > arm > abdominal cavity, retroperitoneum
•Tx: complete excision
•DD: lipoma, atypical lipoma, liposarcoma
Hibernoma
Furlong MA et al Am J Surg Pathol 2001;25:809-14

12. 75 y/o woman with osteoporosis

13. 75 y/o woman with osteoporosis

14. •Long term use of bisphosphonate
•Can also occur without bisphosphonates
•Osteoclast oversuppression → impaired bone remodeling → accumulation of microdamage
•Decreased elasticity, increased brittleness
Atypical femoral fracture

16. sag T1
20 y/o woman with ankle pain
T1
STIR

17. Serous atrophy
•Gelatinous transformation
•Marrow fat not used for energy production
•States of extreme cachexia:
–cancer, chemo tx
–anorexia nervosa
–AIDS
•Marrow fat metabolized, replaced by gelatinous fluid, necrotic on histology
•MRI: marrow SI identical to water
•Cx: stress fx ↔ obscured by abnl. marrow SI