Young adult patient with glycogen storage disease type 1b (homozygous for mutation 12211 delCT in EXON-8), with decades long use of G-CSF for neutrophil dysfunction and neutropenia. 

Current presention is with pain in the left sacro-iliac joint region, with MRI findings consistant with left sacroiliac arthritis.

The MRI further shows diffuse bone marrow signal abnormalities consistant with hypercellularity, with decreased fat component and high T2 signal. Literature suggests that bone marrow hypercellularity is associated with the underlying myeloid dysplasia but markedly increased by the use of G-CSF. 

Patients with this disease may be prone to infections, such as sacroiliac joint arthritis, due to neutrophil dysfunction. The sacroiliac symptoms resolved after antibiotic use and no further diagnostic testing was undertaken. 

A prior non contrast enhanced CT of the abdomen demonstrates the osteopenia and the sparse, course trabecularisation of the lumbar spine and pelvis, along with several extraskeletal manifestations of the underlying metabolic disease.