Chord oma in human beings is an uncommon neopl asm arising from remnants o f the not ochord .' ? It has also been report ed in seve ral animal spec ies, including th e rat ,' 2.,. cat,' dog," m in k," and ferrc t. t-"'? In human being s, cho rdo mas arise pred om inantl y in the sacrococcygeal and sphenooccipita l areas ! In ferr ets, all repo rted cases have been seen at or near the ta il tip .1.6. ' 0 T he purpose of thi s pap er is to describe chordo mas arising in th e cervical spina l region of two ferrets.Case No. I was a 5-yea r-o ld male cas tra ted pet alb ino ferr et with a 4-mo nth history of atax ia in the hind legs th at progressed to pare sis and loss o f propriocepti on. Ov er thi s period, the animal experienced a 25% loss o f bod y weight. At necropsy, th e animal a ppea red mod erat ely cachectic, with m inimal subcutaneo us and intra-abdominal fat stores. Th ere was mild generalized mu scular atro phy, most prominent bilater ally over th e hind limbs. U po n disarticulation o f the atlantoocci pita l joint, a so ft, whitis h gray 1.5-x 1.0-cm amorpho us mass spa nni ng th e artic ular space and th at invo lved th e artic ular facets and exte nded into both the foramen ma gnum and th e verte bra l ca na l of C , and C, was noticed . Addi tiona l gro ss findings in th is ani ma l included moderat e right ventricular dil ati on , hepat ic co ngestion, and spondylosis of th e lumbar spine .Micro scopi c exa mi nation o f sections from th e cervi cal ar ea revealed an infiltrati ve, multilobul at ed ma ss replacing portions of th e vertebral bod y and lamina of C , (F ig. l ) and the ve ntral porti on of the occ ipita l bon e surro undi ng the foram en magnum. Lobules had three com ponents: closely packed vacuolat ed polygon al cells (physa lifero us cells), cartilage, an d bo ne. T he ph ysaliferou s cells were suppo rted by a mu cinou s stro ma o f variable thickness th at blended grad ually with mature carti lage and bone; th e bon e co ntai ned marrow eleme nts. The three co m po nents were frequently arra nged co nce ntr ically within neoplastic lobul es, with ph ysaliferous cells surrounding carti lage with a central core of bon e. Physaliferous cells co nta ined abundant am pho philic foam y cytoplasm and ro und to ova l nucl ei (Fig. 2). Mit oses were rar ely seen. At th e periphery ofl obules, ther e were sma ller, irr egularl y ro und cells with sca nt eos ino philic cyto plasm and simi lar nu clei. T he neopl asm mildl y co m presse d th e sp ina l cor d, and swo l-[en, eosinophilic axo na l rem na nts (spheroi ds) were presen t in sma ll numbers th rou ghout the ventral and lat eral fun iculi. Th e mat rix surro unding the ph ysaliferou s cells stai ned stro ngly for glycosa m inoglyca ns, indi cat ing its cartilagino us nature.Immunohi sto chemi call y, physaliferou s cells conta ined cytok eratin and vime ntin interm ed iat e filame nts but sho wed weak S-I00 prot ein and neu ron-specific eno lase reacti on s.Case No . 2 was a 4-year-old male sab le ferret that initia lly presented wi...