Background and Aims

This is a 63-year-old female patient with a history of acute myeloid leukemia that relapsed after 1 year of treatment. She was treated with a salvage chemotherapy protocol, consolidated with allotransplantation of hematopoietic progenitors (HSCT).

The patient consulted for a 3-week history of marked proximal paraparesis associated with continuous non-radiating low back pain that increased while sitting and with bed-chair transitions.

Musculoskeletal involvement is commonly encountered in Graft-versus-Host Disease (GVHD), including joint/fascia manifestations and neuromuscular complications.

The differential diagnosis of a possible GVHD dermatomyositis versus primary dermatomyositis was considered, and she was hospitalized for etiological study.

Methods

An autoimmunity study was performed based on screening for antinuclear antibodies (ANA) by indirect immunofluorescence, as well as an autoimmune myopathy profile analyzed by immunoblot technique.

Magnetic Resonance Imaging (MRI) of the lower limbs, electromyography and a skin biopsy were also performed.

Results

In the autoimmunity profile we obtained positive ANA with centrosome pattern (AC-24) and positive anti-MDA5 antibodies in the myositis blot. Pre-HSCT tests showed the same ANA pattern but the myositis blot was negative.

Skin biopsy showed interface dermatitis that could not be differentiated between dermatomyositis-like GVHD and primary dermatomyositis.

MRI of the limbs showed a myositis-fasciitis pattern, and the electromyography revealed a primary muscle involvement pattern.

Conclusions

After these findings, the case was classified as a primary dermatomyositis MDA5 post HSCT.

We believe that it`s important to consider that not all cases of inflammatory myopathy after transplantation are GVHD-related, and a diagnosis of primary inflammatory myopathy, although rare, should be considered.