Case Study 47 Julia Kofler, M.D.

Clinical history: The patient is a 67-year-old female with >6 months history of weakness, mostly in proximal muscles. EMG studies were consistent with a myopathy with electrical features of muscle necrosis, inflammation, or membrane irritability. Describe the findings seen on needle biopsy of the deltoid muscle. Click here to view frozen section H&E slide. Click here to view paraffin section H&E slide Click here to view Gomori trichrome slide.here Question 1

Hematoxylin and eosin stained frozen sections reveal mildly increased myofiber size variability without an excess of internalized nuclei. A few scattered atrophic fibers, but no degenerating or regenerating fibers or inflammatory infiltrates are seen. Prominent basophilic stippling is seen in the majority of myofibers. In addition, several fibers contain one or more rimmed vacuoles. H&E stained paraffin sections reveal multiple variably sized vacuoles in most of the fibers. Gomori trichrome highlights the rimmed vacuoles and cytoplasmic stippling but does not reveal ragged red fibers. Answer

Question 2 Which stains may be useful to better define the nature of the vacuoles?

Answer Acid phosphatase Esterase

Question 3 What is highlighted in a muscle biopsy by a positive esterase stain? What is highlighted by acid phosphatase? Based on the results of these stains, which cellular organelle is the origin of the vacuoles in our case? Click here to view esterase slide Click here to view acid phosphatase slide.here

Esterase stain highlights neuromuscular junctions, macrophages, lysosomes and denervated muscle fibers Acid phosphatase stain highlights lysosomes and macrophages For both stains, the staining of macrophages is related to their high content of lysosomes In our case, esterase and acid phosphatase stains highlight the cytoplasmic stippling and vacuoles in some but not all fibers. The results are consistent with autophagic vacuoles of lysosomal origin. Answer

Question 4 Which additional clinical information do you need to obtain to better define the disease process?

Answer Medication history

Question 5 Which drugs are associated with vacuolar myopathies?

Amphiphilic drugs: - Chloroquine, hydroxychloroquine - Amiodarone - Perhexiline maleate Inhibitors of microtubule polymerization: - Colchicine Review of the clinical history in our patient revealed the use of chloroquine Answer

Question 6 Which additional studies can be performed to confirm the diagnosis?

Answer Electron microscopy studies

Question 7 What do you see on the following EM pictures?

Curvilinear bodies, which are characteristic of chloroquine/hydroxychloroquine related myopathy. In some cases, curvilinear bodies can be found in the absence of vacuolar change by light microscopy. Answer

Question 8 What is your final diagnosis?

Autophagic vacuolar myopathy with curvilinear inclusions, consistent with hydroxychloroquine/chloroquine myopathy Answer