[439] Correlation of Axillary Skin and Muscle Biopsy Results in Mitochondrial Cytopathy

CE Baran, RA Prayson. Cleveland Clinic Lerner College of Medicine, Cleveland, OH; Cleveland Clinic Foundation, Cleveland, OH

Background: There is well established, albeit limited, literature documenting the role of axillary skin biopsies (ASB) and skeletal muscle biopsies in the evaluation of metabolic diseases and mitochondrial cytopathy. To our knowledge, no studies have attempted to correlate the results of ASB performed for metabolic diseases and muscle biopsy results, particularly with respect to mitochondrial disorders.
Design: Electron microscopy (EM) files were searched for ASB performed between 1990-2007 for the evaluation of metabolic disease. 536 ASB were performed and comprise the study group. Skin and muscle biopsy (from the same patients (pts)) results, when available, were reviewed to identify mitochondrial alterations.
Results: Of 536 ASB, 64 (11.9%) demonstrated pathologic findings by EM; 31/64 biopsies (48.4%) had mitochondrial abnormalities including large mitochondria (n= 22), expanded matrix material with reduced cristae (n= 21), increased number (n=10), pleomorphism (n=8), lipid droplets (n=3), and presence of dense matrical granules (n=1). 17/31 pts with abnormal mitochondria also had muscle biopsies performed; 7 (41.2%) muscles demonstrated mitochondrial abnormalities including cytochrome oxidase negative fibers (n=2), increased succinate dehydrogenase (SDH) staining (n=2), increased mitochondrial number on EM (n=6), and enlarged mitochondria with abnormal morphology (n=2) on EM. 131/505 pts with normal mitochondria by ASB also had muscle biopsies performed; 58 (44.3%) of these muscles demonstrated mitochondrial abnormalities including increased mitochondrial number (n=45), cytochrome oxidase negative fibers (n=8), increased SDH staining (n=7), ragged red fibers (n=5), and irregular morphology (n=4). Follow-up was available in 26/31 pts with abnormal mitochondria by ASB. A clinical or biochemical diagnosis was reached in 11 pts: electron transport chain abnormalities (n=6), Lennox-Gastaut syndrome (n=1), pyruvate dehydrogenase deficiency (n=1), Charcot-Marie-Tooth disease type 1A (n=1), scleroderma (n=1), and cerebral palsy (n=1).
Conclusions: An ASB is helpful in the evaluation of some mitochondrial disorders, but often the findings are nonspecific. A negative biopsy result does not rule out the possibility of a mitochondrial disorder, but a positive result may provide direction for further evaluation. Muscle biopsies add to the diagnostic yield of the ASB in pts suspected of having mitochondrial cytopathy.
Category: Dermatopathology

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 73, Tuesday Afternoon