Acta Neuropathol (2007) 114:537–542 DOI 10.1007/s00401-007-0217-6 CASE REPORT Myopathy with tubulin-reactive inclusions in two cats G. Diane Shelton · Beverly K. Sturges · Leslie A. Lyons · D. Colette Williams · Monica Aleman · Yun Jiang · Andrew P. Mizisin Received: 26 January 2007 / Revised: 5 March 2007 / Accepted: 6 March 2007 / Published online: 29 March 2007 © Springer-Verlag 2007 Abstract Many types of inclusions have been described Keywords Cats · Myopathy · Crystalline inclusions · in human myopathies including but not limited to nemaline Tubulin rod bodies, cylindrical spirals, tubular aggregates, cytoplas- mic bodies, reducing bodies, and Wngerprint bodies, and hyaline inclusions in myoWbrillar myopathy and inclusion Introduction body myositis. There are very few reports describing inclu- sions in spontaneously occurring myopathies in cats, and Inclusions described in human myopathies include nema- these reports are limited to nemaline rod myopathy. A line rod bodies, cylindrical spirals, tubular aggregates, cyto- myopathy with tubulin-reactive crystalline inclusions has plasmic bodies, reducing bodies, Wngerprint bodies, and recently been reported in a human patient with a clinical hyaline inclusions in myoWbrillar myopathy and inclusion presentation of myalgia and fatigue. Similarly, a myopathy body myositis [2]. These inclusions may be the primary with chronic, slowly progressive muscle weakness has been pathologic change as in myopathies associated with nema- identiWed here in two unrelated cats. Inclusions were the line rods, tubular aggregates or cylindrical spirals [9], or only pathological change in skeletal muscle biopsies and, may be associated with other myopathic abnormalities as in ultrastructurally, groups of crystalline structures were evi- myoWbrillar myopathy [11] and inclusion body myositis dent that had a subsarcolemmal or central location, rhom- [1]. Inclusions may be characteristic of a speciWc myopa- boid or rectangular shapes, lacked orientation, and were not thy, or may occur in various myopathies, such as the Wnd- membrane bound. The crystalline structures reacted posi- ing of tubular aggregates in disorders as diverse as periodic tively with an antibody against tubulin. This feline myopa- paralysis, congenital myasthenic syndromes, and muscle thy may be the equivalent of the human myopathy with disorders associated with pain, cramps, or stiVness. tubulin-positive crystalline inclusions. There are very few reports describing inclusions in spon- taneously occurring myopathies in cats, and these reports are limited to nemaline rod myopathy. There is one report of a congenital nemaline myopathy in a family of cats [3] in which nemaline rods were the primary pathologic abnor- G. D. Shelton (&) · Y. Jiang · A. P. Mizisin Department of Pathology 0709, mality. There is also a single case report of a myopathy in a University of California, San Diego, La Jolla, cat in which rod bodies were found in conjunction with the CA, 92093-0709, USA accumulation of other proteins including desmin, dystro- e-mail: [email protected] phin and spectrin [7]. B. K. Sturges · D. C. Williams · M. Aleman A myopathy with tubulin-reactive crystalline inclusions Veterinary Medical Teaching Hospital, has been reported in a human patient with myalgia, mildly University of California, Davis, Davis, CA, USA elevated serum creatine kinase concentrations (2–5 times the reference range), and fatigue [13]. Examination of cryo- L. A. Lyons Department of Population Health and Reproduction, stat sections of muscle showed aggregates of small crystal University of California, Davis, Davis, CA, USA inclusions in the sarcoplasm of type 2 Wbers. The inclusions 123 538 Acta Neuropathol (2007) 114:537–542 were eosinophilic and stained bright red with the modiWed frightened, it would occasionally lose its balance and fall to Gomori trichrome stain, indicating a membranous compo- the Xoor, struggle and be unable to get up. At the time of nent. Ultrastructurally, the crystals were randomly oriented, presentation to the VMTH, the owner was unsure whether rhomboidal or rectangular, and not membrane bound. the signs had progressed in severity, although they did Immunohistochemical studies showed strong reactivity of seem to wax and wane. the inclusions to antibodies against tubulin. In addition, Abnormalities noted on physical examination included subsarcolemmal rhomboid or rectangular crystalline struc- signs of chronic upper respiratory infection and a body con- tures have been described in muscle from two human dition score of 3/9 indicative of mild-to-moderate general- patients with diabetic amyotrophy and neuropathy [12], and ized muscle wasting (1, extreme emaciation; 5, ideal body cystine crystals described in Wbroblasts in nephropathic weight; 9, extreme obesity). On neurological examination, cystinosis [6]. the cat had normal mentation and cranial nerve function. Recently, light microscopic, immunohistochemical, and Although it was able to walk and run without apparent diY- ultrastructural changes similar to the reported human culty, it would sit or lie down whenever possible. When sit- myopathy [13] were identiWed in muscle biopsies from two ting, it assumed a characteristic pose (Fig. 1a). The cat had cats with chronic, slowly progressive muscle weakness. mild cervical ventroXexion and, when supporting the head, Here we analyze the inclusions in detail and report that, in would appear to use momentum to swing and move it. In a these two cats, the sarcoplasmic crystalline inclusions also sitting or lying position, it would immediately Wnd some- react with anti-tubulin antibody. These observations point thing in the environment to rest its head on (Fig. 1b). The to the likelihood that this myopathy is the feline equivalent remainder of the neurologic exam was normal, as were a of the human myopathy. routine complete blood count, serum biochemical proWle including creatine kinase (CK) concentration, and a urinal- ysis. Electromyography, done under general anesthesia, Case descriptions showed no spontaneous activity or abnormal insertional activity. Waveform conWguration and motor and sensory Case 1 nerve conduction velocities were within normal limits for the feline peroneal nerve. Cord dorsum potentials and late A 4-year-old female spayed Devon Rex cat was donated to waves were present, and repetitive stimulation (1, 2, 3, 5, 7, the Veterinary Medical Teaching Hospital (VMTH), Uni- 10, 15, 20, 30, and 50 Hz) did not show a signiWcant decre- versity of California, Davis because of generalized weak- mental response. Biopsies of the quadriceps, cranial tibial ness and episodes of “spastic” behavior. The cat was and triceps muscles were obtained, as well as a biopsy of obtained from a breeder at 8 months of age, and was thin the peroneal nerve. and underweight. It also had a severe upper respiratory infection that was a recurrent problem. The cat had diY- Case 2 culty in swallowing soft foods and would often gag while eating. Whenever it was picked up, its legs would become A 6-year-old male neutered domestic shorthaired cat was stiV and grope wildly until Wnding something on which to presented with a 1-year history of slowly progressive weak- cling. Although able to ambulate without assistance, it was ness and generalized muscle atrophy. Weakness began ini- much weaker than the other cats in the household. When tially in the pelvic limbs and then progressed to Fig. 1 A 4-year-old female spayed Devon Rex (cat 1) with myopathy associated with crystalline inclusions in muscle Wbers. When sitting, it assumed a characteristic position (a). In a lying position, it would immediately Wnd something in the environment to rest its head on (b) 123 Acta Neuropathol (2007) 114:537–542 539 tetraparesis. General physical examination was considered sections stained with uranyl acetate and lead citrate for normal, and routine blood counts and serum chemistry electron microscopy. analyses including CK concentration were within reference ranges. With the exception of weakness and muscle atro- ImmunoXuorescence phy, the neurological examination was unremarkable with normal spinal reXexes and sensations, and normal mental After washing with 0.05 M Tris buVer solution (TBS, pH attitude and cranial nerve functions. An electromyogram 7.6) containing 0.2% Triton-X (TBST), the 8 m thick sec- was performed and revealed no abnormalities in insertional tions were blocked with 10% goat serum for 30 min. The activity or waveforms. Measurement of the tibial motor sections were then incubated with one of the following pri- nerve conduction velocity and amplitude of the compound mary antibodies in TBST containing 5% goat serum over- muscle action potential was within the reference range for night at 4°C: rabbit antibodies against desmin (1:20, cats. As a neuromuscular disease was suspected, muscle D8281, Sigma, St Louis, MO), -amyloid (1:200, 51–2700, and peripheral nerve biopsies were performed. Zymed, South San Francisco, CA), and ubiquitin (1:250, Z0458, DakoCytomation, Carpinteria, CA), mouse antibod- ies against myeloid leukemia factor 1 (MLF1, 1:100, Methods Abgent, San Diego, CA), two mouse antibodies against - tubulin (1:2000, T6074, Sigma, St Louis, MO; 1:1000, gift Histopathology and histochemistry from Dr. Donald Cleveland, University of California, San Diego), and a rat anti-tubulin antibody against the tyrosi- Immediately following collection, muscle biopsy samples nated form of -tubulin (1:2000, gift from Dr. Donald (cranial tibial, triceps, and quadriceps