Histopathologic Features and Post-surgical Sequelae

Vet !'ath ol 30:6. 1993 Skin Tumors in Ferrets 503
The preputial gland and anal gland neoplasm s were
compatible with apocrine gland adenocarcino mas. The
preputial gland ade nocarcino ma was inoperabl e, and
the animal was eutha natized. T here was no reported
recurre nce or metastasis of the ana l gland adc nocarcmo
rna.
The preputial lym phosarco ma (tumor No . 56) was
a 2-cm -diame ter ulcerat ed mass involving the prepuce,
but not the peni s, of a 6-year-old intact male. Microscopically,
the prepuce and inguinal lymph node had
sheets ofindividualized round neoplastic cells that had
a small amount of cytoplasm , coarsely clumped chroma
tin , promi nent nu cleoli, and num erous mitoti c figures
that were co mpatible with th ose of mod erately
differentiated Iymphoblasts. Post-operat ive clin ical inform
ati on was not available.
Th e cuta neo us polyp (tumor No . 57) was a 3-mmd
iame ter mass on the right metat arsus of a 5-year-old
fem ale. Microscopica lly, the polypoid lesion consisted
ofa central zo ne offibrous connective tissue and blood
vessels covered by well-differentiated stratified squamou
s epithelium . T here was no reported recurrence or
me tas tasis.
Discussion
Cutaneous neopl asm s were co m mo n findin gs in biopsy
or necrop sy speci me ns fro m dom estic ferrets submitted
to diagnostic lab oratories and comprised 46%
of accessions in a 54-mont h period. T he mos t common
cutaneous neopl asm in th is study was basal cell tumor
33/57 (58%), followed by mastocytoma 9/57 ( 16%) and
fibro ma 6/57 (I I%). Previo us case reports 9. 11. 15.22 have
suggested that cutaneous squamous cell carci noma is
co m mo n in ferrets, no squa mo us cell carcino mas were
found in the present study. Th e grea t majorit y of the
basal cell tumors in this study included areas o f squamous
differe ntiation , but the basaloid components were
so prominent that the neop lasm s would not be c1assilled
as squamous cell carci no ma s by accepted classificatio
n criteria.
T he basal cell neoplasms were micro scopically similar
to those seen in dogs '? and to the ferre t neoplasm s
previou sly reported as basisqu amosebaceou s and sebaceou
s gland carcino mas. 19.20 T hese two term s are descriptive
of many of the lesion s seen in th e present
study , but the term " basal cell tumor " was chose n to
reflect the co m mo n origin ofthe tumors fro m basaloid
ep ithelial cells. There were no pigm ent ed or cystic basal
cell tumors, such as th ose seen in dom estic cats.v"
There was no distinct site predilection, altho ugh the
head, neck, sho ulders , legs, and feet were somewhat
more commonly involved than expected, give n the
relative surface area of ski n involved. In the overall
gro up of 142 ferrets with cuta neo us and noncutan eou s
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lesions, 58% were females, but 70% offerrets with basal
cell tumors were female.
T he ma stocytomas were microscopically benign and
were sim ilar to th ose previou sly reported in ferr ets.
T he mastocytomas were simi lar to th ose seen in domestic
cats, although the ferret lesion s lacked the follicular
lymphocytic aggregatio ns that are commonly
seen in solitary cuta neo us mastocyto mas of cats.P-"
T he sing le multicentric histiocytic mastocytoma resembled
the histiocytic variant of mastocytoma that
is most commo nly seen in Siamese cats." The ferret
mastocytomas lacked the prom inent eosinophilic infiltratio
n, ede ma , and collagen dege neratio n that are
commonly seen in canine cuta neo us mastocytomas."
Mast cell gra nules of rode nts and human beings have
an a ffi nity for av idi n th at can be dem on strat ed by sta ndard
immunohi stochemi cal sta ining procedures.v' and
avidin affinity has been reported as a method for differen
tia ting mastocytomas from other ro und cell tu ­
mors in the dog and ca1. 3 • 18 Findings in the present
stud y indicate that some ferre t mas tocytomas have
affini ty for avi din; however, avi di n stai ning had no
d iagnostic advantage over ro utine staining wit h toluidine
blue for me tachromasia.
T he fibro mas and fibrosarcomas were simi lar to those
reported in other species. The degree of cellular atypism
and mitoti c ind ex were th e basis for classificati on
oftwo masses as fibrosa rcomas, although th ose lesio ns
d id not appear to be highly aggressive.
T his study provides no conclusive information regarding
the overall prevalence ofneoplasia in the ferre t
beca use the size of the general population from whic h
these cases were derived was unknown. Cutaneous neoplasms
were commonly found among speci me ns subm
itted for ro utine histopath ologic diagnos is, but specime
ns ofthat type would be expected to contai n a large
percentage of neopl asm s. Th ese features of th e study
prohibit us from confirmi ng or refuti ng the prop osal
th at the ferre t is a low tumor incidence species.
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