Brief Communications and Case Reports
Vet Pathol 29(4), 1992
Primary tumors in the neurohypophysis should be differentiated both from tumors that occur in adjacent structures and infiltrate into the neurohypophysis and from metastases. The small size of the tumor and its confinement to the neurohypophysis ruled out tumor origination in surrounding tissues. Meningioma was ruled out by positive staining for GFAP and S100. No other tumors were observed in the animal, making a metastatic tumor unlikely. Two varieties of primary neurohypophyseal tumors are recognized: astrocytomas and granular cell tum01-s.~ Astrocytomas arise from pituicytes, the neurohypophyseal glial cells, which are considered astrocytes by most investigator^.^ Astrocytomas from the neurohypophysis are also known as pituicytomas. Granular cell tumors are characterized by plump oval cells with periodic acid-Schiff-positive cytoplasmic granules. These cells may be modified astrocytes, but their exact lineage is still a matter of debate.9 This tumor was diagnosed as an astrocytoma, based on histologic findings and positive staining for GFAP. Positive staining for GFAP, vimentin, and S 100, as seen in this tumor, is commonly seen in human astrocytoma~.~.~ The variation in staining intensity among individual tumor cells indicates differences in the quantity of intermediate filaments and S 100 protein and may reflect the degree of differentiation of the tumor cells. An inverse relationship between the malignancy of glial cell tumors and the level of GFAP expression has been ~uggested.~ Well-documented cases of primary astrocytomas in the neurohypophysis have been reported in human beings,8,10 rats,2 and a Siamese cat." These tumors may cause clinical symptoms by compression or invasion of adjacent tissues. No evidence of clinical disease related to the tumor was observed in this rhesus monkey. This is the first report of such a tumor in a nonhuman primate.
Acknowledgement
36 1
2 Carlton WW, Gries CL: Pituicytoma, neurohypophysis, rat. In: Endocrine System, ed. Jones TC, Mohr U, and Hunt RD, pp. 156-1 60. Springer-Verlag, Berlin, Germany, 1983 3 Herpers MJHM, Ramaekers FCS, Aldeweireldt J, Moesker A, Slooff J: Co-expression of glial fibrillary acidic protein- and vimentin-type intermediate filaments in human astrocytomas. Acta Neuropathol70:333-339, 1986 4 Jacque CM, Kujas M, Poreau A, Raoul M, Collier P, Racadot J, Baumann N: GFA and S 100 protein levels as an index for malignancy in human gliomas and neurinomas. J Natl Cancer Inst 62479-483, 1979 5 Lapin BA: Use of nonhuman primates in cancer research. J Med Primatol 11:327-341, 1982 6 Lowenstine LJ: Neoplasms and proliferative disorders in nonhuman primates. In: Primates: The Road to Selfsustaining Populations, ed. Benirscke K, pp. 78 1-8 14. Springer-Verlag, Berlin, Germany, 1986 7 Luna L, ed.: AFIP Manual of Histologic Staining Methods, 3rd ed., p. 39. Armed Forces Institute of Pathology, Washington, DC, 1968 8 Rossi ML, Bevan JS, Esiri MM, Hughes JT, Adams CBT: Pituicytoma (pilocytic astrocytoma). J Neurosurg 62768772, 1987 9 Russell DS, Rubinstein LJ: Pathology of Tumours of the Nervous System, 5th ed., pp. 376-378. E. Arnold, London, England, 1989 10 Scothorne C: A glioma of the posterior lobe of the pituitary gland. J Pathol Bacteriol 69:109-112, 1955 11 Zaki F, Harris J, Budzilovich G: Cystic pituicytoma of the neurohypophysis in a Siamese cat. J Comp Pathol 85:46747 1, 1975 Request reprints from Dr. H. HogenEsch, Institute for Aging and Vascular Research, PO Box 430, 2300CK Leiden (The Netherlands).
We thank Mr. T. Glaudemans for photographic assistance.
References 1 Beniashvili DS: An overview of the world literature on spontaneous tumors in nonhuman primates. J Med Primatol 1fk423-437, 1989
Vet Pathol29:361-363 (1992)
Eastern Equine Encephalomyelitis in an Adult Cow E. D. MCGEE,C. H. LITTLETON, J. B. ~LIAPP,AND R. J. BROWN Key words: Cow; eastern equine encephalomyelitis; nonsuppurative encephalitis. A 1%-year-old crossbred beef cow submitted alive to the Mississippi Board of Animal Health Veterinary Diagnostic Laboratory had been recumbent for 2 days. The cow could stand with assistance but circled to the left when walking. No other animals from the herd of 125 had been affected,
and there had been no additions to the herd within the previous 8 months. An ante mortem complete blood count revealed a mild inflammatory neutrophilia and a normal total leukocyte count (1 1,700 total leukocytes, 7,020 neutrophils, 468 band neu-
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
362
Brief Communications and Case Reports
Vet Pathol 29(4), 1992
Fig. 1. Ventral midbrain. Note the prominent perivascular cuffs, microglial nodules, and a diffuse increase in microglia. HE. Bar = 100 pm. Fig. 2. Ventral midbrain. There is a small perivascular cuff (lower right), an ill-defined microglial nodule (arrow), and a varied, diffuse increase in microglia. HE. Bar = 25 pm.
trophils, 3,978 lymphocytes, 234 monocytes, and no eosinophils or basophils per microliter). Elevated serum aspartate aminotransferase (1,4 14 IUAiter) with normal serum alkaline phosphatase and serum gamma glutamyl transferase was attributed to recumbency. Other values from a 16-chemistry panel were within normal limits. Blood lead levels were not detectable. The cow was euthanatized and necropsied. No gross lesions were found. Histologic lesions were limited to the central nervous system. Sections examined included temporal cerebral cortex, hippocampus, occipital cerebral cortex, ventral midbrain at the level of the rostra1 colliculus, left trigeminal ganglion, pons and cerebellar hemisphere at the level of the cerebellar peduncles, and spinal cord at the level ofthe second cervical vertebra. Lesions were similar in nature but most severe in the ventral midbrain and pons, mild to moderate in the cerebral cortex and hippocampus, and minimal in the spinal cord. Lesions in the ventral midbrain (Figs. 1, 2) and pons included severe lymphohistiocytic perivascular cuffing, moderate regionally diffuse rarefaction of the neuropil, scattered microglial nodules, and rare neuronophagia. Mild focal accumulations of lymphocytes in the meninges were noted adjacent to areas with the most severe involvement. Neutrophils were present in very low numbers and were only found within the most prominent perivascular cuffs. The hippocampus contained scattered microglial nodules and neuronophagia, mild diffuse microglia, and variable lymphohistio-
cytic perivascular cuffs. Sections of temporal and occipital cerebral cortex contained scattered microglial nodules, mild diffuse microglia, and rare neuronophagia. Perivascular cuffing was moderate in the temporal cortex and mild in the occipital cortex and adjacent white matter. The cervical spinal cord changes were limited to mild perivascular cuffing and minimal microgliosis of the gray matter. Lesions were not found in the cerebellar hemisphere or in the trigeminal ganglion. Serologic tests for antibodies to pseudorabies, infectious bovine rhinotracheitis(IBR),and bovine virus diarrhea (BVD) were negative. Direct fluorescent antibody staining of frozen sections from the ventral midbrain, pons, and temporal and occipital cortices with conjugates for IBR, BVD, and rabies viral antigens yielded negative results. After 16 hours of incubation, homogenates of combined nervous tissues produced small foci of cytopathic effect in Vero cell monolayers, but not in bovine turbinate cell monolayers. Direct fluorescent antibody staining of Vero cell cultures was negative for IBR, BVD, and rabies viral antigens but was positive with the indirect fluorescent antibody technique for eastern equine encephalomyelitis (EEE) viral antigen. Duplicate tissues and homogenates referred to the National Veterinary Services Laboratory (NVSL, Ames, IA) confirmed these results by the identification of a togavirus interpreted to be EEE virus based on electron microscopy and complement fixation testing of the homogenate (Dr. D. Pederson, NVSL, Ames, IA, personal communication).
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
Vet Pathol 29(4), 1992
Brief Communicatioiis and Case Reports
363
Differential diagnoses for nonsuppurative encephalitis in neutrophils. Alternatively, the antigenic stimulus may have bovine species include rabies, pseudorabies, malignant ca- primarily elicited a lymphohistiocytic response rather than tarrhal fever, sporadic bovine encephalomyelitis, IBR, and a neutrophilic response, perhaps because of differences in BVD.l.2.5Neither gross nor histologic lesions considered char- antigenic modulation or processing. EEE virus should be considered as a sporadic cause of acteristic of these diseases were found in the appropriate tissues. IBR as a cause of encephalitis has been found in encephalitis with lymphohistiocytic perivascular cuffing in neonates but is most common in calves 4 to 7 months of adult cattle. age. I Occasional lymphohistiocytic perivascular infiltrates References were seen in cattle 5 to 34 months of age with persistent BVD infection, although BVD antigen was not found in those infiltrates. Focal satellitosis around degenerating neurons was 1 Divers TJ: Infectious causes of meningitis a& encephalitis in cattle. In: Current Veterinary Therapy, Food Andescribed but is of uncertain significance.2 imal Practice, ed. Howard JL, 2nd ed., pp. 854-855. WB The isolation of EEE virus has been reported from pigeons, Saunders, Philadelphia, PA, 1986 monkeys, human beings, rodents, insects, Pharo and bobwhite quail, ring-necked pheasants, dogs, goats, pigs, and 2 Fernandez A, Hewicker M, Trautwein G, Pohlenz J, Liess B: Viral antigen distributionin the central nervous system The lesions in quail, pheasants, dogs, goats, pigs, of cattle persistently infected with bovine viral diarrhea and horses are described as neuronal degeneration and nevirus. Vet Pathol 26:26-32, 1989 crosis, small glial nodules around injured neurons, and a 3 Pursell AR, Hall RF, Sangster LT, Waller E, Bedell DM: prominent neutrophilic infiltration.) The neutrophilic infilEastern encephalomyelitis: the Georgia experience 1982trate was considered to be a consistent feature of EEE infec83. Proc Annu Meet Am Assoc Vet Lab Diagn 26:383tion in all of these species and was especially severe in the 392, 1983 cerebral cortex, as is seen in horses. EEE virus was isolated 4 Pursell AR, Mitchell FE, Siebold H R Naturally occurring from two naturally infected calves, 1 and 6 weeks of age, and experimentally induced eastern encephalomyelitis in with a prominent neutrophilic infiltration of the n e ~ r o p i l . ~ calves. J Am Vet Med Assoc 169: 1101-1 103, 1976 These reports emphasize the young age ofthe affected species, the acute clinical disease leading to death (12 hours to 4 days), 5 Sullivan ND: The nervous system. In: Pathology of Domestic Animals, ed. Jubb KVF, Kennedy PC, and Palmer and a prominent neutrophilic infiltration. Differences in this N, 3rd ed., vol. 1, pp. 290, 295, 297, 301, 304. Academic case include the mature age of the cow and the lack of a Press, Orlando, FL, 1985 significant neutrophilic infiltrate. The progress of the clinical illness in this case was unrecognized prior to recumbency, which may have provided adequate time for the perivascular Request reprints from Dr. E. D. McGee, Mississippi Board cuffs to shift from predominantly neutrophilic infiltration to of Animal Health, Veterinary Diagnostic Laboratory, PO predominantly lymphohistiocytic, with only a few remaining Box 4389, Jackson, MS 392 16 (USA).
Vet Pathol 29:363-365 (1992)
Cutaneous Mastocytosis in a Dog B. J. DAVIS, R. PAGE,P. L. SANNES,AND D. J. MEUTEN Key words: Cutaneous mastocytosis; urticaria pigmentosa; dog. Mastocytosis refers to a disorder of unknown origin characterized by an abnormal proliferation of systemic or cutaneous mast cells. A cutaneous form has been described in a foal,2 and a pig.6 Cutaneous mastocytosis in chilIn the foal and dren is referred to as urticaria pigment~sa.~ the kittens, and in children, the cutaneous lesions regressed spontaneously. A male Jack Russell Terrier developed multiple cutaneous masses at 3 weeks of age and was pruritic and lethargic. Biopsies taken from two nodules when the puppy was 10 weeks old contained moderate numbers of round cells. The cells formed a nonencapsulated, poorly circumscribed mass that blended with adjacent tissues. A large amount of edema separated these cells from each other. The cells formed rows
as they dissected between collagen fibers or they coalesced into sheets. The round cells had abundant amphophilic to eosinophilic cytoplasm in sections stained with hemotoxylin and eosin and had numerous metachromatic cytoplasmic granules when stained with toluidine blue. Nuclei were usually central and were oval or indented. Chromatin was clumped, and some nuclei contained faint nucleoli. Eosinophils were scattered throughout both nodules. One section contained an extensive ulcer and numerous neutrophils in the subjacent dermis. The diagnosis was mastocytosis. At 13 weeks of age, the dog was still lethargic and pruritic and had approximately ten discrete cutaneous masses ranging from 1 to 5 cm in diameter on its head, neck, legs, perineum, and trunk. Masses varied considerably in their gross ap-
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
Vet Pathol 29(4), 1992
Primary tumors in the neurohypophysis should be differentiated both from tumors that occur in adjacent structures and infiltrate into the neurohypophysis and from metastases. The small size of the tumor and its confinement to the neurohypophysis ruled out tumor origination in surrounding tissues. Meningioma was ruled out by positive staining for GFAP and S100. No other tumors were observed in the animal, making a metastatic tumor unlikely. Two varieties of primary neurohypophyseal tumors are recognized: astrocytomas and granular cell tum01-s.~ Astrocytomas arise from pituicytes, the neurohypophyseal glial cells, which are considered astrocytes by most investigator^.^ Astrocytomas from the neurohypophysis are also known as pituicytomas. Granular cell tumors are characterized by plump oval cells with periodic acid-Schiff-positive cytoplasmic granules. These cells may be modified astrocytes, but their exact lineage is still a matter of debate.9 This tumor was diagnosed as an astrocytoma, based on histologic findings and positive staining for GFAP. Positive staining for GFAP, vimentin, and S 100, as seen in this tumor, is commonly seen in human astrocytoma~.~.~ The variation in staining intensity among individual tumor cells indicates differences in the quantity of intermediate filaments and S 100 protein and may reflect the degree of differentiation of the tumor cells. An inverse relationship between the malignancy of glial cell tumors and the level of GFAP expression has been ~uggested.~ Well-documented cases of primary astrocytomas in the neurohypophysis have been reported in human beings,8,10 rats,2 and a Siamese cat." These tumors may cause clinical symptoms by compression or invasion of adjacent tissues. No evidence of clinical disease related to the tumor was observed in this rhesus monkey. This is the first report of such a tumor in a nonhuman primate.
Acknowledgement
36 1
2 Carlton WW, Gries CL: Pituicytoma, neurohypophysis, rat. In: Endocrine System, ed. Jones TC, Mohr U, and Hunt RD, pp. 156-1 60. Springer-Verlag, Berlin, Germany, 1983 3 Herpers MJHM, Ramaekers FCS, Aldeweireldt J, Moesker A, Slooff J: Co-expression of glial fibrillary acidic protein- and vimentin-type intermediate filaments in human astrocytomas. Acta Neuropathol70:333-339, 1986 4 Jacque CM, Kujas M, Poreau A, Raoul M, Collier P, Racadot J, Baumann N: GFA and S 100 protein levels as an index for malignancy in human gliomas and neurinomas. J Natl Cancer Inst 62479-483, 1979 5 Lapin BA: Use of nonhuman primates in cancer research. J Med Primatol 11:327-341, 1982 6 Lowenstine LJ: Neoplasms and proliferative disorders in nonhuman primates. In: Primates: The Road to Selfsustaining Populations, ed. Benirscke K, pp. 78 1-8 14. Springer-Verlag, Berlin, Germany, 1986 7 Luna L, ed.: AFIP Manual of Histologic Staining Methods, 3rd ed., p. 39. Armed Forces Institute of Pathology, Washington, DC, 1968 8 Rossi ML, Bevan JS, Esiri MM, Hughes JT, Adams CBT: Pituicytoma (pilocytic astrocytoma). J Neurosurg 62768772, 1987 9 Russell DS, Rubinstein LJ: Pathology of Tumours of the Nervous System, 5th ed., pp. 376-378. E. Arnold, London, England, 1989 10 Scothorne C: A glioma of the posterior lobe of the pituitary gland. J Pathol Bacteriol 69:109-112, 1955 11 Zaki F, Harris J, Budzilovich G: Cystic pituicytoma of the neurohypophysis in a Siamese cat. J Comp Pathol 85:46747 1, 1975 Request reprints from Dr. H. HogenEsch, Institute for Aging and Vascular Research, PO Box 430, 2300CK Leiden (The Netherlands).
We thank Mr. T. Glaudemans for photographic assistance.
References 1 Beniashvili DS: An overview of the world literature on spontaneous tumors in nonhuman primates. J Med Primatol 1fk423-437, 1989
Vet Pathol29:361-363 (1992)
Eastern Equine Encephalomyelitis in an Adult Cow E. D. MCGEE,C. H. LITTLETON, J. B. ~LIAPP,AND R. J. BROWN Key words: Cow; eastern equine encephalomyelitis; nonsuppurative encephalitis. A 1%-year-old crossbred beef cow submitted alive to the Mississippi Board of Animal Health Veterinary Diagnostic Laboratory had been recumbent for 2 days. The cow could stand with assistance but circled to the left when walking. No other animals from the herd of 125 had been affected,
and there had been no additions to the herd within the previous 8 months. An ante mortem complete blood count revealed a mild inflammatory neutrophilia and a normal total leukocyte count (1 1,700 total leukocytes, 7,020 neutrophils, 468 band neu-
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
362
Brief Communications and Case Reports
Vet Pathol 29(4), 1992
Fig. 1. Ventral midbrain. Note the prominent perivascular cuffs, microglial nodules, and a diffuse increase in microglia. HE. Bar = 100 pm. Fig. 2. Ventral midbrain. There is a small perivascular cuff (lower right), an ill-defined microglial nodule (arrow), and a varied, diffuse increase in microglia. HE. Bar = 25 pm.
trophils, 3,978 lymphocytes, 234 monocytes, and no eosinophils or basophils per microliter). Elevated serum aspartate aminotransferase (1,4 14 IUAiter) with normal serum alkaline phosphatase and serum gamma glutamyl transferase was attributed to recumbency. Other values from a 16-chemistry panel were within normal limits. Blood lead levels were not detectable. The cow was euthanatized and necropsied. No gross lesions were found. Histologic lesions were limited to the central nervous system. Sections examined included temporal cerebral cortex, hippocampus, occipital cerebral cortex, ventral midbrain at the level of the rostra1 colliculus, left trigeminal ganglion, pons and cerebellar hemisphere at the level of the cerebellar peduncles, and spinal cord at the level ofthe second cervical vertebra. Lesions were similar in nature but most severe in the ventral midbrain and pons, mild to moderate in the cerebral cortex and hippocampus, and minimal in the spinal cord. Lesions in the ventral midbrain (Figs. 1, 2) and pons included severe lymphohistiocytic perivascular cuffing, moderate regionally diffuse rarefaction of the neuropil, scattered microglial nodules, and rare neuronophagia. Mild focal accumulations of lymphocytes in the meninges were noted adjacent to areas with the most severe involvement. Neutrophils were present in very low numbers and were only found within the most prominent perivascular cuffs. The hippocampus contained scattered microglial nodules and neuronophagia, mild diffuse microglia, and variable lymphohistio-
cytic perivascular cuffs. Sections of temporal and occipital cerebral cortex contained scattered microglial nodules, mild diffuse microglia, and rare neuronophagia. Perivascular cuffing was moderate in the temporal cortex and mild in the occipital cortex and adjacent white matter. The cervical spinal cord changes were limited to mild perivascular cuffing and minimal microgliosis of the gray matter. Lesions were not found in the cerebellar hemisphere or in the trigeminal ganglion. Serologic tests for antibodies to pseudorabies, infectious bovine rhinotracheitis(IBR),and bovine virus diarrhea (BVD) were negative. Direct fluorescent antibody staining of frozen sections from the ventral midbrain, pons, and temporal and occipital cortices with conjugates for IBR, BVD, and rabies viral antigens yielded negative results. After 16 hours of incubation, homogenates of combined nervous tissues produced small foci of cytopathic effect in Vero cell monolayers, but not in bovine turbinate cell monolayers. Direct fluorescent antibody staining of Vero cell cultures was negative for IBR, BVD, and rabies viral antigens but was positive with the indirect fluorescent antibody technique for eastern equine encephalomyelitis (EEE) viral antigen. Duplicate tissues and homogenates referred to the National Veterinary Services Laboratory (NVSL, Ames, IA) confirmed these results by the identification of a togavirus interpreted to be EEE virus based on electron microscopy and complement fixation testing of the homogenate (Dr. D. Pederson, NVSL, Ames, IA, personal communication).
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
Vet Pathol 29(4), 1992
Brief Communicatioiis and Case Reports
363
Differential diagnoses for nonsuppurative encephalitis in neutrophils. Alternatively, the antigenic stimulus may have bovine species include rabies, pseudorabies, malignant ca- primarily elicited a lymphohistiocytic response rather than tarrhal fever, sporadic bovine encephalomyelitis, IBR, and a neutrophilic response, perhaps because of differences in BVD.l.2.5Neither gross nor histologic lesions considered char- antigenic modulation or processing. EEE virus should be considered as a sporadic cause of acteristic of these diseases were found in the appropriate tissues. IBR as a cause of encephalitis has been found in encephalitis with lymphohistiocytic perivascular cuffing in neonates but is most common in calves 4 to 7 months of adult cattle. age. I Occasional lymphohistiocytic perivascular infiltrates References were seen in cattle 5 to 34 months of age with persistent BVD infection, although BVD antigen was not found in those infiltrates. Focal satellitosis around degenerating neurons was 1 Divers TJ: Infectious causes of meningitis a& encephalitis in cattle. In: Current Veterinary Therapy, Food Andescribed but is of uncertain significance.2 imal Practice, ed. Howard JL, 2nd ed., pp. 854-855. WB The isolation of EEE virus has been reported from pigeons, Saunders, Philadelphia, PA, 1986 monkeys, human beings, rodents, insects, Pharo and bobwhite quail, ring-necked pheasants, dogs, goats, pigs, and 2 Fernandez A, Hewicker M, Trautwein G, Pohlenz J, Liess B: Viral antigen distributionin the central nervous system The lesions in quail, pheasants, dogs, goats, pigs, of cattle persistently infected with bovine viral diarrhea and horses are described as neuronal degeneration and nevirus. Vet Pathol 26:26-32, 1989 crosis, small glial nodules around injured neurons, and a 3 Pursell AR, Hall RF, Sangster LT, Waller E, Bedell DM: prominent neutrophilic infiltration.) The neutrophilic infilEastern encephalomyelitis: the Georgia experience 1982trate was considered to be a consistent feature of EEE infec83. Proc Annu Meet Am Assoc Vet Lab Diagn 26:383tion in all of these species and was especially severe in the 392, 1983 cerebral cortex, as is seen in horses. EEE virus was isolated 4 Pursell AR, Mitchell FE, Siebold H R Naturally occurring from two naturally infected calves, 1 and 6 weeks of age, and experimentally induced eastern encephalomyelitis in with a prominent neutrophilic infiltration of the n e ~ r o p i l . ~ calves. J Am Vet Med Assoc 169: 1101-1 103, 1976 These reports emphasize the young age ofthe affected species, the acute clinical disease leading to death (12 hours to 4 days), 5 Sullivan ND: The nervous system. In: Pathology of Domestic Animals, ed. Jubb KVF, Kennedy PC, and Palmer and a prominent neutrophilic infiltration. Differences in this N, 3rd ed., vol. 1, pp. 290, 295, 297, 301, 304. Academic case include the mature age of the cow and the lack of a Press, Orlando, FL, 1985 significant neutrophilic infiltrate. The progress of the clinical illness in this case was unrecognized prior to recumbency, which may have provided adequate time for the perivascular Request reprints from Dr. E. D. McGee, Mississippi Board cuffs to shift from predominantly neutrophilic infiltration to of Animal Health, Veterinary Diagnostic Laboratory, PO predominantly lymphohistiocytic, with only a few remaining Box 4389, Jackson, MS 392 16 (USA).
Vet Pathol 29:363-365 (1992)
Cutaneous Mastocytosis in a Dog B. J. DAVIS, R. PAGE,P. L. SANNES,AND D. J. MEUTEN Key words: Cutaneous mastocytosis; urticaria pigmentosa; dog. Mastocytosis refers to a disorder of unknown origin characterized by an abnormal proliferation of systemic or cutaneous mast cells. A cutaneous form has been described in a foal,2 and a pig.6 Cutaneous mastocytosis in chilIn the foal and dren is referred to as urticaria pigment~sa.~ the kittens, and in children, the cutaneous lesions regressed spontaneously. A male Jack Russell Terrier developed multiple cutaneous masses at 3 weeks of age and was pruritic and lethargic. Biopsies taken from two nodules when the puppy was 10 weeks old contained moderate numbers of round cells. The cells formed a nonencapsulated, poorly circumscribed mass that blended with adjacent tissues. A large amount of edema separated these cells from each other. The cells formed rows
as they dissected between collagen fibers or they coalesced into sheets. The round cells had abundant amphophilic to eosinophilic cytoplasm in sections stained with hemotoxylin and eosin and had numerous metachromatic cytoplasmic granules when stained with toluidine blue. Nuclei were usually central and were oval or indented. Chromatin was clumped, and some nuclei contained faint nucleoli. Eosinophils were scattered throughout both nodules. One section contained an extensive ulcer and numerous neutrophils in the subjacent dermis. The diagnosis was mastocytosis. At 13 weeks of age, the dog was still lethargic and pruritic and had approximately ten discrete cutaneous masses ranging from 1 to 5 cm in diameter on its head, neck, legs, perineum, and trunk. Masses varied considerably in their gross ap-
Downloaded from vet.sagepub.com at Monash University on March 6, 2015
