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Cutaneous lymphoproliferative diseases encompass a spectrum of lesions, ranging from self-limiting, reactive infiltrates to high-grade lymphomas. In humans, cutaneous lymphocytosis (CL) refers to self-limiting or slowly progressive monomorphic lymphocytic infiltrates of mostly unknown cause. It morphologically mimics cutaneous lymphoma. CL in cats also is a slowly progressive disease. Immunophenotyping and clonality testing of feline CL support an indolent lymphoma for the majority of cases studied. This study reports CL in dogs. Erythematous, scaly and alopecic macules, patches or plaques were present in eight dogs. Breed predilection was not observed; six of eight dogs were females; and ages ranged from 5 to 14 years. Diffuse monomorphic non-epitheliotropic infiltrates of CD3(+) (eight of eight), CD45(-) (four of eight) or CD45(+/-) (four of eight) and CD45RA(-) (seven of eight) T lymphocytes were present in the superficial and mid-dermis. Further immunophenotyping of five cases revealed TCR-gammadelta(+) T cells (one of five) or TCR-alphabeta(+) (four of five) T cells. TCR-alphabeta(+) populations were either CD8(+) (two of four) or CD4(-)CD8(-) (2/4). Clonality testing found clonal (seven of eight) or pseudoclonal (one of eight) rearrangement of the TCR-gamma locus of the lesional T cells. Prednisone, prednisolone and methylprednisolone acetate were the most commonly administered drugs. The lesions remained stable for long periods up to 6 years. Five dogs were euthanized due to progression of the skin lesions (three of five), peripheral lymphadenopathy of unknown origin (one of five) or high-grade lymphoma (one of five). One dog was lost for follow-up and two dogs are still alive (17 and 9 months after diagnosis). Canine CL is best considered an initially indolent lymphoma, with slow progression and a potential for progression to high-grade lymphoma.

Clinical, morphological and immunohistochemical features of cutaneous lymphocytosis, an uncommon disease histologically resembling well-differentiated malignant lymphoma, were characterized in 23 cats. Clinical outcome was correlated with histomorphology and immunophenotype in an attempt to predict benign vs. malignant behaviour. The disease mainly affected older cats. Lesions were solitary in 61% of cats and often characterized by alopecia (73.9%), as well as erythema, scaling and ulceration. The lateral thorax was most commonly affected (43.5%). Pruritus was frequent (65.2%). Systemic signs included anorexia and weight loss. Morphologically, lesions were characterized by dermal infiltrations of well-differentiated CD3+ T-cells (100%) and aggregates of CD79+ B-cells (64.3%). Cutaneous lymphocytosis is slowly progressive and relatively benign, although in some cats systemic signs led to euthanasia. Four of 12 euthanized cats and one live cat also had lymphoid infiltrates in internal organs. Unfortunately, we were unable to predict clinical outcome by histological and immunohistochemical evaluations of skin lesions.

A novel form of mural folliculitis is described in seven cats. Clinically, all cats exhibited generalized alopecia with scaling or crusting that was more pronounced over the head, neck, and shoulders. The face and muzzle of all cats was unusually thickened. Six of seven cats were progressively lethargic but did not demonstrate any other consistent systemic abnormalities. Histologically, there was severe mixed inflammation of the wall of the follicular isthmus in all cats, accompanied by some follicular destruction in five cats. Sebaceous glands were not affected. All cats had variable, but often striking, follicular mucin deposition, as well as epidermal hyperkeratosis and crusting. The cause of the severe mural folliculitis was not identified, and all cats responded poorly to immunomodulating therapy. Follicular mucinosis may be a nonspecific finding, likely reflective of the follicular lymphocytic milieu, and does not always herald follicular lymphoma.

Systemic lupus erythematosus (SLE) was diagnosed in a 9-year-old castrated male Persian cat. The cat described is the first to fulfil four of 11 American Rheumatism Association criteria for the diagnosis of SLE in humans (symmetrical facial dermatitis, thrombocytopenia, positive antinuclear antibodies, oral ulceration) with supportive skin histopathology. Haematological abnormalities included a mild anaemia and severe thrombocytopenia. Skin disease consisted of symmetrical multifocal alopecia with crusting, predominantly on the face. Histopathology of the skin revealed interface dermatitis and interface folliculitis with follicular atrophy. Complete remission was obtained with corticosteroid therapy.

Six adult dogs were presented with an unusual bullous dermatosis affecting the glabrous skin of the ventral abdomen and medial thighs. Clinically, flaccid bullae were accompanied by erythema, ulceration, haemorrhage and hyperpigmentation in four of six dogs; the remaining two dogs had thin skin without grossly apparent bullae. Histologically, subepidermal bullae and clefting, vascular proliferation and dilatation (phlebectasia), and alteration in the density and staining of superficial dermal collagen were seen in all dogs. In all cases, corticosteroid-containing topical products had been applied to the affected areas prior to the development of the dermatosis; skin lesions resolved when topical corticosteroids were withdrawn. Follow-up biopsy of three dogs showed resolution of the previously abnormal collagen and subepidermal clefting. Residual lesions included phlebectasia, comedones and hyperpigmentation. The authors postulate that subepidermal clefting was due to local, corticosteroid-induced skin fragility. This is the first report, to our knowledge, of bullous skin disease in dogs resulting from topical corticosteroid therapy.

A young Lhasa Apso was presented with lameness, resulting from calcinosis circumscripta of the metatarsal and metacarpal pads. Renal failure was detected by analysis of serum chemistry; concurrent hypercalcaemia and hyperphosphataemia were present. Renal dysplasia was evident upon post-mortem examination. Calcinosis circumscripta was a likely manifestation of metastatic calcification. Because soft tissue calcification in renal failure may be partly dystrophic in nature, pawpad involvement in this dog may have resulted from conformational stresses that allowed damage to these tissues. This is the first report of calcinosis circumscripta associated with canine renal dysplasia. Resume— Un jeune Lhassa Apso est presente en consultation pour une bolterie due a une calcinose circonscrite des coussinets metatarsiens et metacarpiens. Une insuffisance renale a ete retrouvee sur le bilan biochimique, qui demontrait a la fois une hypercalcemie et une hyperphosphatemie. L'autopsie a revele une dysplasie renale. La calcinose circonscrite etait vraisemblablement une manifestation de calcification metastatique. Comme la calcification des tissus mous de l'insuffisance renale est partiellement de nature dystrophique, il est possible que l'atteinte des coussinets chez ce chien ait ete le resultat de stress qui ont entraine une alteration de ces tissus. C'est le premier cas decrit de calcinose circonscrite associea une dysplasie renale chez le chien. [Gross, L.T. Calcinosis circumscripta and renal dysplasia in a dog. (Calcinose circonscrite et dysplasie renale chez un chien.) Veterinary Dermatology 1997; 8: 27–32.] Resumen Se presento un Lasha Apso joven con una cojera debida a calcinosis circumscripta de los cojinetes metatarsianos y metacarpianos. Se detecto fallo renal mediante el analisis de bioquimica serica; existia hipercalcemia e hiperfosfatemia concurrentes. El examen post mortem hizo evidente una displasia renal. La calcinosis circumscripta era una manifestacion probable de calcificacion metastatica. Puesto que la calcification de tejidos blandos en el fallo renal puede ser parcialmente de naturaleza distrofica, la afectacion de los cojinetes palmares y plantares en este perro pudo haber resultado del estres en la conformation de los tejidos, permitiendo el dano de los mismos. Este es el primer caso descrito de calcinosis circumscripta asociada a la displasia renal en el perro. [Gross, L.T. Calcinosis circumscripta and renal dysplasia in a dog. (Calcinosis circumscripta y displasia renal en un perro.) Veterinary Dermatology 1997; 8: 27–32.] Zusammenfassung— Ein junger Lhasa Apso wurde wegen Lahmheit vorgestellt, die durch eine Calcinosis circumscripta der Metatarsal-und Metakarpalballen verursacht wurde. Das Nierenversagen wurde bei der Analyse des Blutserums entdeckt; eine gleichzeitige Hyperkalzamie und Hyperphosphatamie waren vorhanden. Die Nierendysplasie wurde bei der Sektion offensichtlich. Die Calcinosis circumscripta war wahrscheinlich eine Manifestation einer metastaslerenden Kalzifizierung. Da Weichtellkalzlfizierung bei Nierenversagen teilweise dystropher Natur sein kann, kann die Beteiligung der Pfotenballen bei diesem Hund durch Anpassungsstres verursacht sein, weicher Schaden dieser Gewebe ermoglichte. Dies ist der erste Bericht uber eine Calcinosis circumscripta in Verbindung mit Nierendysplasie beim Hund. [Gross, L.T. Calcinosis circumscripta and renal dysplasia in a dog. (Calcinosis circumscripta und Nierendysplasie bei einem Hund.) Veterinary Dermatology 1997; 8: 27–32.]

A paraneoplastic alopecia associated with internal malignancy is reported in four cats. Acute, bilaterally symmetrical, ventral glistening alopecia, weight loss and lethargy were present in all cats. Skin biopsy specimens exhibited severe follicular and adnexal atrophy with follicular miniaturization, minimal inflammation and, in many cases, absence of stratum corneum. At the time of diagnosis, three cats had a metastatic pancreatic adenocarcinoma and one had a bile duct carcinoma. This report confirms, and expands upon the previous report of a syndrome associating ventral alopecia and metastatic visceral carcinomas in cats. Resume— Une alopecie paraneoplasique associee a une tumeur interne maligne est observee sur 4 chats. Les symptomes sont caracterises par une alopecie symetrique et bilaterale sur le ventre avec un aspect brillant et lisse, un amaigrissement, une lethargic Les lesions histopathologiques sont caracterisees par une atrophie folliculaire et annexielle avec des petits follicules pileux, une inflammation dermique discrete et dans beaucoup de cas, une absence du stratum corneum. Trois chats presentent un adenocarcinome pancreatique metastase et un chat un cholangiocarcinome. Ces cas confirment l'existence d'un syndrome associant une alopecie ventrale et des carcinomes visceraux metastatiques chez le chat. [Pascal-Tenorio, A., Olivry, T., Gross, T. L., Atlee, B. A., Ihrke, P. J. Paraneoplastic alopecia associated with internal malignancies in the cat. (Alopecie paraneoplasique associee a des tumeurs malignes internes chez le chat.) Veterinary Dermatology 1997; 8: 47–52.] Resumen Se describe en cuatro gatos una alopecia paraneoplasica asociada a procesos malignos internos. Todos los gatos presentaban una alopecia bilateral, simetrica, ventral, de aspecto brillante, perdida de peso y letargia. Las biopsias cutaneas mostraron atrofia folicular y adnexal marcada, miniaturizacion de foliculos, inflamacion minima y, en muchos casos, ausencia del estrato corneo. En el momento del diagnostico, tres de los gatos tenian un adenocarcinoma metastatico y uno tenia un carcinoma de conducto biliar. Este articulo confirma y amplia un informe previo sobre el sindrome de alopecia ventral y carcinomas viscerales metastaticos en gatos. [Pascal-Tenorio, A., Olivry, T., Gross, T. L., Atlee, B. A., Ihrke, P. J. Paraneoplastic alopecia associated with internal malignancies in the cat. (Alopecia paraneoplasica asociada a procesos malignos internos en el gato.) Veterinary Dermatology 1997; 8: 47–52.] Zusammenfassung— Es wird uber eine paraneoplastische Alopezie in Verbindung mit inneren malignen Prozessen bei vier Katzen berichtet. Bei alien Katzen traten eine akute bilateral symmetrische ventrale Alopezie, Gewichtsverlust und Lethargie auf. Die Hautbiopsien zeigten eine schwere follikulare und adnexale Atrophie mit follikularer Miniaturisation, geringer Entzundung und in vielen Fallen ein Fehlen des Stratum corneum. Zum Zeitpunkt der Diagnose litten drei Katzen an einem metastasierenden Adenokarzinom des Pankreas und eine Katze an einem Gallengangskarzinom. Dieser Bericht erhartet und erweitert den fruheren Bericht uber ein Syndrom, das ventrale Alopezie in Verbindung mit metastasierenden Eingeweidekarzinomen bei der Katze beschreibt. (Paraneoplastische Alopezie in Verbindung mit inneren malignen Prozessen bei der Katze.) Veterinary Dermatology 1997; 8: 47–52.]

Follicular lipidosis is reported in three young Rottweilers that developed hypotrichosis of the mahogany-coloured points of the face and feet. One dog had concurrent lightening and dulling of the remaining hair. Hair matrix cells were swollen with intracellular lipid, identified by electron microscopy and oil-red-O staining. Concurrent abnormalities in one dog included poor somatic growth and elevation in serum concentration of blood urea nitrogen and creatinine. Necropsy of this dog revealed small thyroid glands with no visible colloid production, and chronic renal disease. The two remaining dogs were otherwise healthy. One of these two dogs had partial resolution of the hair loss with persistence of mild histological changes of the hair follicles 7 months after first presentation. The second was lost to follow-up but written records had no mention of skin lesions at presentation for cruciate repair 3 years after initial recognition of the haircoat changes. To the authors' knowledge, this is the first report of follicular lipidosis in any species. Resume— Une lipidose folliculaire est observee sur trois jeunes Rottweilers qui developpent une hypotrichose des zones acajou de la face et des pieds. Un chien presente egalement un eclaircissement et un aspect terne des poils restant. Les cellules matricielles des poils sont gonflees par des lipides en position intracellulaire identifies par la microscopie electronique et une coloration au Rouge Congo. D'autres symptomes sont observes chez un chien: retard de croissance et des elevations de l'uremie et de la creatininemie. L'autopsie de ce chien a montre des glandes thyroidiennes petites et une insuffisance renale chronique. Les deux autres chiens sont en bonnes sante. Un des deux chiens a presente une resolution partielle de l'hypotrichose avec une persistance moderee des modifications histopathologiques des follicules, sept mois apres la premiere visite. Le second a ete perdu de vue mais des contacts par ecrit ont permis de savoir que le chien ne presentait plus de lesions, trois ans apres la premiere visite. A la connaissance de l'auteur, il s'agit de la premiere description de lipidose folliculaire. [Gross, T. L., Pascal-Tenorio, A., Munn, R. J., Hargis, A. M., Kline, A. Follicular lipidosis in three Rottweilers. (Lipidose folliculaire chez trois Rottweilers.) Veterinary Dermatology 1997; 8: 33–40.] Zusammenfassung— Bei drei jungen Rottweilern, die Hypotrichie an den mahagonifarbenen Stellen im Gesicht und an den Pfoten entwickelten, wird von follikularer Lipidose berichtet. Einer der Hunde hatte gleichzeitig eine Aufhellung und Abstumpfung des ubrigen Haarkleides. Haarmatrixzellen waren mit intrazellularem Lipid angeschwollen, das mittels Elektronenmikroskopie und ‘oil-Red-O’ Farbung identifiziert wurde. Bei einem Hund waren gleichzeitig schlechtes somatisches Wachstum und erhoehte Harnstoff-und Kreatininspiegel im Serum feststellbar. Nekropsie dieses Hundes ergab kleine Schilddrusen ohne wahrnehmbare Kolloidproduktion und chronische Nierenerkrankung. Die zwei anderen Hunde wareii ansonsten gesund. Das Haarkleid einer der beiden Hunde wuchs teilweise wieder, leichte histologische Veranderungen waren 7 Monate nach der ersten Unetersuchung immer noch vorhanden. Der zweite Fall wurde nicht weiterverfolgt, jedoch erwahnten die Krankenberichte 3 Jahre nach dem Beginn der Haarkleidveranderungen keine diesbezuglichen Anomalien. Soviel die Autoren wissen, ist dieses der erste Bericht uber follikulare Lipidose bei Tieren. [Gross, T. L., Pascal-Tenorio, A., Munn, R. J., Hargis, A. M., Kline, A. Follicular lipidosis in three Rottweilers. (Folliculare Lipidose bei 3 Rottweilern.) Veterinary Dermatology 1997; 8: 33–40.] Resumen Se describio una lipidosis folicular en tres Rottweilers jovenes que desarrollaron hipotricosis en los puntos color caoba de la cara y patas. Uno de los perros tenia a su vez el resto del pelo mas claro y mate. Les celulas de la matriz del pelo se encontraban tumefactas, con lipido intracelular identificado mediante microscopia electronica y tincion roja-O. Un perro presentaba concomitantement crecimiento somatico deficiente y elevaciones sericas de BUN y creatinina. El estudio de necropsia en este perro revalo glandulae tiroides de pequeno tamano, sin produccion de coloide visible, asi como enfermedad renal cronica. Los otros dos animales se encontraban en buen estado de salud. Uno de ellos experimento una resolucion parcial de la perdida de pelo con persistencia de alteraciones histologicas leves de los foliculos 7 meses despues de la primera presentacion. No fue posible el seguimiento del segundo perro, pero no se mencionaban lesiones cutaneas en el informe escrito del animal al presentarse 3 anos despues para una intervencion de ligamentos cruzados, despues de la alteraciones iniciales. Segun nuestros datos, esta es la primera descripcion de lipidosis folicular en cualquier especie. Gross, T. L., Pascal-Tenorio, A., Munn, R. J., Hargis, A. M., Kline, A. Follicular lipidosis in three Rottweilers. (Lipidosis folicular en tres Rottweilers.) Veterinary Dermatology 1997; 8: 33–0.]

Seven Dachshunds from five different families were studied for late-onset alopecia. All were born blue and tan in litters containing unaffected wild boar coated animals. Six of the seven dogs changed their colour during the first months of their life from blue and tan to ‘deadleaf’ or grey and tan. Histopathology, light microscopy of hairs and scanning electron microscopy of the hairs showed similarities with those previously described in blue Doberman Pinschers and confirmed the diagnosis of colour dilution alopecia (CDA). Transmission electron microscopy of cross-sectioned hairs showed vacuoles containing melanin granules of different size in medullary, subcortical and intracortical areas. Some opened at the hair surface and released melanin granules. Study of the pedigree proved autosomal recessive inheritance. Resume— 7 teckels de 5 families ont fait l'objet de cette etude. Tous sont nes bleu et feu et proviennent de portees comprenant des chiots sains couleur sanglier. Six de ces chiens ont change leur couleur durant les premiers mois de leur vie, passant ainsi du bleu et feu a‘feuilles mortes’ ou gris et feu. Histologiquement, l'examen microscopique des poils et l'examen ultrastructural a balayage montrent des lesions similaires a celles decrites chez les Dobermanns Pinschers bleus, et confirment le diagnostic d'Alopecie des Robes Diluees (ARD). La microscopie electronique a transmission des poils sectionnes montre des vacuoles contenant des grains de melanine dans les regions medullaires, subcorticales, et intracorticales des poils. Quelques poils montrent la sortie des granules de melanine a la surface du poil. L'etude des pedigres prouve un mode de transmission autosomal recessif de cette maladie. [Beco, L., Fontaine, J., Gross, T.L., Charlier, G. Colour dilution alopecia in seven Dachshunds. A clinical study and the hereditary, microscopical and ultrastructural aspects of the disease (Alopecie des Robes Diluees chez 7 teckels: etude clinique et aspects hereditaires, microscopiques et ultrastructuraux). Veterinary Dermatology 1996; 7: 91–97.] Resumen Se estudio la alopecia de aparicion tardia en siete perros Dashshund de cinco familias diferentes. Todos los cachorros nacieron de color azul y canela en camadas que contenian animates con pelaje jabali, sin afectacion. Seis de los siete perros cambiaron su color durante los primeros meses de vida de azul y canela a ‘hoja seca’ o gris y canela. La histopatologia, la microscopia optica de los pelos y la microscopia electronica de barrido de los pelos mostraron similitudes con los previamente descritos en los Doberman Pinscher azules y confirmaron el diagnostico de alopecia de color diluido (ACD). La microscopia electronica de transmision de cortes transversales del pelo mostraron vacuolas que contenian granulos de melanina de tamano variable en las zonas medular, subcortical e intracortical. Algunos se abrian a la superficie del pelo y liberaban granulos de melanina. El estudio del pedigree revelo una forma de herenicia autosomica recesiva. [Beco, L., Fontaine, J., Gross, T.L., Charlier, G. Colour dilution alopecia in seven Dachshunds. A clinical study and the hereditary, microscopical and ultrastructural aspects of the disease (Alopecia de color diluido en siete Dachshunds. Estudio clinico y aspectos hereditarios, microscopicos y ultraestructurales de la enfermedad). Veterinary Dermatology 1996; 7: 91–97.] Zusammenfassung— Sieben Dackel aus funf verschiedenen Familien wurden wegen Alopezie mit spatem Beginn untersucht. Alle wurden als ‘blau und tan’ in Wurfen geboren, die gesunde saufarbene aufwiesen. Sechs der sieben Hunde anderten ihre Farbe wahrend der ersten Lebensmonate von ‘blau und tan’ nach ‘durrlaub’ oder ‘grau und tan’. Histopathologisch zeigten Lichtmikroskopie der Haare und Elektronen-mikroskopabtastung der Haare Ahnlichkeiten mit denen fruher beschriebener Veranderungen beim blauen Dobermann, und bestatigten die Diagnose Farbverdunnungsalopezie (CDA). Die Transmissionselek-tronenmikroscopie von quergeschnittenen Haaren zeigte Vakuolen, die Melaningranula verschiedener Grose in medullaren, subkortikalen und intrakortikalen Zonen enthielten. Einige offneten sich hin zur Haarober flache und entliesen die Melaningranula. Die Untersuchung der Abstammung zeigte eine autosomal rezessive Erblichkeit. [Beco, L., Fontaine, J., Gross, T. L., Charlier, G. Colour dilution alopecia in seven dachschunds. A clinical study and the hereditary microscopical and ultrastructural aspects of the disease (Farbverdunnungsalopezie bei sieben Dackeln. Eine klinische Studie uber erbliche, mikroskopische und ultrastrukturelle Aspekte dieser Erkrankung). Veterinary Dermatology 1996; 7: 91–97.]

Resume— Une urtricaire due a la diethylcarbamazine associee a une dermite prurigineuse a ete suspectee chez un chien mâle castre croise Retriever. L'animal presentait des lesions d'urticaire multiples qui avaient tendance a fusionner au niveau des paupieres, des levres, les conques auriculaires et du prepuce. Les biopsies cutanees ont revele un infiltrat perivasculaire et periannexiel intense riche en polynucleaires eosinophiles. Parfois les polynuclaires eosinophiles etaient “degranules” ou presentaient des formes “en flamme”. La suppression de l'administration de diethylcarbamazine a ete suivie d'une disparission rapide de toutes les lesions cutanees. L'hypothese d'une reaction immune a la diethylcarbamazine est proposee. [Vitale, C. B., Ihrke, P. J., Gross, T. L. Putative diethylcarbamazine-induced uticaria with eosinophilic dermatitis in a dog. (Probable urticaire et dermite eosinophilique induites par la diethylcarbamazine chez un chien). Resumen— Se describe el caso de un perro macho castrado, cruzado de retriever que presentaba una dermatitis pruritica con urticaria supuestamente inducida por dietilcarbamacina. El perro mostraba multiples habones, principalmente alrededor de los ojos, la boca, los pabellones auriculares y el prepucio. El estudio histologico mostro un infiltrado perivascular y perianexal, con predominancia de eosinofilos. Ocasionalmente los eosinofilos degranulaban formando “figuras en llama”. La retirada de la terapia con dietilcarbamacina fue seguida por una mejoria rapida y espectacular de todas las lesiones cutaneas. Se postula una reaccion adversa a la dietilcarbamacina mediada por factores inmunologicos. [Vitale, C. B., Ihrke, P. J. and Gross, T. L. Putative diethylcarbamazine-induced urticaria with eosinophilic dermatitis in a dog (Urticaria con dermatitis eosinofilica supuestamente inducida por dietilcarbamacina en un perro). Zusammenfassung— Es wird uber eine vermutlich Diethylcarbamazin-verursachte Urtikaria mit Juckreiz bei einem mannlich-kastrierten Retrievermischling berichtet. Der Hund wies generalisiert multifokale Striemen auf, die dazu tendierten um Augen, Mund, Ohrmuscheln und Praputium zusammenzulaufen. Die Hautbiopsie zeigte ein starkes perivaskulares und periadenxales Infiltrat mit vorwiegend eosinophilen Granulozyten. Gelegentlich degranulierten die Eosinophilen zu “Flammenform”. Das Absetzen von Diethylcarbamazin fuhrte zu einer dramatischen und raschen Abheilung aller Hautveranderungen. Es wird eine immunologischvermittelte Arzneimittelreaktion auf Diethylcarbamazin vermutet. [Putative diethylcarbamazine-induced utricaria with eosinophilic dermatitis in dogs (Vermutlich Diethylcarbamazin-verursachte Urtikaria mit eosinophiler Dermatitis beim Hund). Abstract— A suspected diethylcarbamazine-induced urticarial dermatitis with associated pruritus is reported in a castrated male mixed breed retriever. The dog had generalized multifocal wheals that tended to cluster around the eyes, mouth, pinnae, and prepuce. Skin biopsy revealed an intense perivascular and periadnexal infiltrate with eosinophils predominating. On occasion, eosinophils degranulated to form “flame figures”. Withdrawal of diethylcarbamazine resulted in dramatic and rapid resolution of all skin lesions. An immunologically mediated adverse drug reaction to diethylcarbamazine is proposed.

— Giant cell dermatosisis is reported in six cats with evidence of concurrent feline leukemia virus (FeLV) infection. Scaling, crusting and alopecia, accompanied by pruritus, affected the head and/or face predominantly in most cats; generalized skin disease developed in one cat. Histologically, giant keratinocytes resembling syncytial cells were found in the epidermis and superficial hair follicles, and were accompanied by dyskeratosis, pustules and ulcers. Immunohistochemical staining revealed FeLV antigen in the giant cells and adjacent keratinocytes. FeLV infection may have led to neoplastic alteration of the keratinocytes through recombination with host oncogenes Resumen Este articulo se basa en seis gatos con dermatosis de las celulas gigantes infectados con el virus FeLV. Estos animales presentaban escamas y costras, asi como perdida de pelo y picor en las regiones de la cabera y cara, predominantemente. Tan solo uno de los gatos desarrollo una dermatosis generalizada. En el examen histologico se demostro la presencia de keratinocitos gigantes con semejonza a las celulas sinticiales localizados en la epidermis y foliculos pilosos superficiales, acompanados de disqueratosis, pustulas y ulceras. Las finturas histo-inmunologicas demostraron el antigeno FeLV en las celulas gigantes y keratinocitos adyacentes. La injeccion con el virus FeLV pudo haber conducido a la alteracion neoplastica de los keratinocitos a traves de la recombinacion con los oncogenes del hospedador.

A rare congenital dermatosis, characterized by progressive hypotrichosis with variable scaling and crusting, occurred in 10 short-haired kittens in North America and Europe. Lesions appeared at between 4 and 12 weeks of age, commencing on the head and becoming generalized. The tail was spared in two kittens. Generalized scaling was mild to moderate, often with prominent follicular casts. Periocular, perioral, pinnal and ear canal crusting was occasionally severe. The skin was thick and wrinkled in two kittens. Histologically, the main lesion was abnormal sebaceous gland morphology. Instead of regular differentiation from basal cells to mature sebocytes, the glands were composed of a haphazard collection of undifferentiated basaloid cells, some partly vacuolated and a few containing eosinophilic globules. Mitotic figures and apoptotic cells were present in an irregularly thickened follicular isthmus. Lymphocytic mural folliculitis and mild sebaceous adenitis were rare. Orthokeratotic hyperkeratosis and follicular casts were present. Hair follicles were of normal density and were mostly in anagen, but some contained malacic hair shafts. Perforating folliculitis, leading to dermal trichogranuloma formation, occurred occasionally. Further biopsy samples taken at 2 years and at 3 and 4 years, respectively, from two kittens revealed similar but often more severe sebaceous gland lesions. Hair follicles were smaller, with many in telogen. The young age of onset suggests a genetic defect interfering with sebaceous and, possibly, follicular development. These lesions are discussed with reference to studies of mouse mutants in which genetic defects in sebaceous differentiation cause a similar phenotype of hyperkeratosis and progressive alopecia.

Angiomatosis, a heterogeneous group of potentially progressive, non-neoplastic, possibly congenital vascular proliferations, has not been well documented in dogs and cats. The pathogenesis of angiomatosis is largely unknown. The lesions can be categorized as progressive angiomatosis (PA), scrotal-type vascular hamartoma (STVH), or angiomatosis secondary to lymphedema (ASL). Spontaneous regression has not been seen. Irregular, red to blue macules, patches, nodules and plaques may partially blanch with diascopy. Periodic hemorrhaging may occur. Progressive angiomatosis may develop at any age and most often affects the extremities, but may occur elsewhere. Breed or sex predilections are not known. Canine STVH affects middle-aged or older dogs and develops on the scrotum, tail or caudal trunk. Breeds with pigmented scrotal skin are predisposed. Angiomatosis secondary to lymphedema is a rare condition affecting extremities. Progressive angiomatosis is characterized by interconnected foci of dermal and subcutaneous blood-filled vascular structures of variable size, separated by normal or myxomatous mesenchymal tissue. The vascular channels may have large lumens or resemble capillaries and are lined by mature or slightly enlarged endothelial cells. Thrombosis and intraluminal papillary endothelial hyperplasia may be present. Variable amounts of smooth muscle and fibrous tissue indicate the presence of arterioles and veins. With STVH, clusters are composed of central larger vessels surrounded by capillary buds. With ASL, there is marked lymphedema, primary hypoplasia of the deep lymphatics, and prominent secondary vascular proliferation. Most forms of canine and feline angiomatoses are newly recognized syndromes; as more cases are gathered and documented, nomenclature and classification may change. Funding: Self-funded.

A previous study described cutaneous lymphocytosis (CL) in 23 cats. The process resembles cutaneous pseudolymphoma in humans, a heterogeneous group of benign reactive proliferations of well-differentiated lymphocytes in the skin of humans. Morphological and immunophenotypic characteristics do not offer reliable criteria to accurately predict the clinical outcome of feline CL or pseudolymphoma in humans. Presence of clonal cell populations is more consistent with a neoplastic process. In a previous study, feline CL lesions (20 cats) were evaluated for clonality using PCR, and only two cats had monoclonal T-cell populations. Because false-negative results may occur, the purpose of this study was to repeat the PCR using a revised primer set based on analysis of additional feline T-cell receptor γ (TCRγ) sequences. DNA was isolated from 29 skin lesions and six internal organs of 20 cats. DNA integrity was assessed by glyceraldehyde-3-phosphate dehydrogenase PCR. Polymerase chain reaction clonality was performed using the revised primer set specific for feline TCRγ, and duplicate samples were evaluated. The PCR products were assessed by heteroduplex analysis. Clonal rearrangement of TCRγ was detected in 14 cats (24 of 35 tissues: 21 of 29 skin lesions and three of six internal organs); eight of these cats are still alive and six were euthanized. Monoclonal populations were seen in three of five cats that had involvement of internal organs. These findings indicate that feline CL is best considered as a slowly progressive process which may be reactive, but often evolves into a low-grade indolent lymphoma. Funding: George H. Muller Fund for Research in Dermatology.