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Joint Pathology Center Veterinary Pathology Services WEDNESDAY SLIDE CONFERENCE 2015-2016 C o n f e r e n c e 11 9 December 2015 Elizabeth Mauldin, DVM, , DACVP Associated Professor of Pathology and Dermatology University of Pennsylvania School of Veterinary Medicine Philadelphia, PA CASE I: N1400608 (JPC 4066457). amount of hair remained over the inguinal, axillary, and perianal regions and the distal Signalment: Mature gravid female white- extremities. There was consolidation and tailed deer (Odocoileus virginianus). dark red to black discoloration of the right cranial lung lobe. The remainder of the History: This doe was found dead, but was thoracic and abdominal viscera was grossly observed alive in the same yard the previous normal. evening. Laboratory Results: None Gross Pathology: Approximately 95% of the skin was alopecic, hyperpigmented, and Histopathologic Description: Diffusely, covered by small coalescing crusts. A small there is a defect in hair development. Hair shafts are frequently absent from follicles; remaining hair shafts are angular or kinked, attenuated, and fragmented, and rarely extend to follicular ostia at the skin surface. The hair cortex is composed of Skin, white-tailed deer. Approximately 95% of the skin was alopecia and hyperpigmented with hyaline, relatively small amounts of hair remaining over the inguinal, axillary, and perianal regions as well as thinned keratin. the distal extremities. (Photo courtesy of: University of Pennsylvania, School of Veterinary Medicine, Department of Pathobiology, http://www.vet.upenn.edu/research/academic- Follicular infundibula departments/pathobiology/pathology-toxicology Haired skin, white-tailed deer. Hair follicles are empty or contain fragmented, poorly formed hair shafts and keratin debris. Diffusely sebaceous glands are hyperplastic, and apocrine glands are dilated by excessive secretory product. HE, 55X). are multifocally dilated and misshapen, and reportedly arisen in the Great Lakes region some are filled with excessive orthokeratin. and the Mississippi Valley.5 Despite there Occasional hair bulbs and inferior portions being some knowledge of this entity for of hair follicles are present at the level of the decades, little has been determined as to a infundibular-isthmic junction. Sebaceous cause, including an underlying genetic glands are multifocally hyperplastic, with defect. Moreover, to date there are no cases ectatic ducts that contain fragments of described in the primary literature, and there keratin debris. There is mild dermal are no similar reports in other cervid inflammation with few scattered species.5 The likely cause of death in this lymphocytes and histiocytes. The epidermis case was attributed to the regional is variably mildly acanthotic and bronchopneumonia. hyperpigmented. This condition calls into question the distinction between follicular dystrophy and Contributor’s Morphologic Diagnosis: dysplasia. A true follicular dystrophy Haired skin: Follicular dysplasia, diffuse suggests a degenerative process and possible association with ‘malnutrition’ of hair Name of disease: Toothpaste hair disease follicle cells.7 The result is defective and of white-tailed deer impaired development of hair in spite of a structurally normal hair follicle. In contrast, Contributor’s Comment: Toothpaste hair follicular dysplasias not only feature disease of the white-tailed deer is a rare abnormal hairs but are also accompanied by 5 condition sporadically affecting individuals abnormal hair follicles. While this entity with features of widespread alopecia and has been classified as a form of follicular multifocal crusts. Previous cases have dystrophy in the past, we consider a diagnosis of follicular dysplasia appropriate another follicular dystrophy phenotype has in this case given the occasional abnormal been defined in B6.C mice, resulting from morphology of hair bulbs, and their often the Angora mouse mutation brought about aberrant location within the superficial by a deletion in fibroblast growth factor 5 dermis. In prior cases of toothpaste hair (Fgf5) gene.10 disease, a direct link with malnutrition, though suspected, has not been confirmed. Humans are also subject to follicular A nutrient/mineral assay was not performed dystrophies. An entity known as acquired on tissues from the present case. progressive kinking of hair is an androgen- dependent disorder that causes affected hairs Follicular dysplasias are not uncommon in veterinary medicine. Color dilution alopecia and black hair follicular dysplasia are well- described conditions in various breeds of dog and cattle.1 The former has also been reported in the horse.4 Non-color dependent follicular dysplasias have also been reported for various dog breeds including Siberian huskies, Irish water spaniels, and Portugese water dogs amongst others. The hairlessness trait of the Sphynx cat and Chinese crested and Mexican hairless dogs is another widely recognized form of follicular dysplasia daired skin, white-tailed deer. Dysplastic follicles (congenital hypotrichosis) brought about by occasionally contain small, misformed hair shafts which the intentional propagation of spontaneous lack a distinct cuticle, cortex, and medulla. (HE, 268X) genetic mutations.1 Hair cycle disorders of the scalp to resemble pubic hair in (including cyclic flank alopecia and 9 follicular arrest) are also classified by some morphology. A subset of follicular dystro- to be follicular dysplasias. phies are known to stem from deficiencies in one of various nutrients, including copper (Menke’s kinky hair syndrome), sulfur Follicular dystrophies are comparatively (trichothiodystrophy), and amino acids quite rare. There are several well- (Netherton’s syndrome).5 characterized follicular dystrophies in mice. Recently, a spontaneous autosomal recessive mutation was discovered on mouse JPC Diagnosis: Haired skin and subcutis: chromosome 2, termed follicular dystrophy Follicular dysplasia with sebaceous gland (fold), affecting the P/J mouse strain.3 A hyperplasia, duct dilation and primary follicular dystrophy has also been hyperkeratosis. described in a substrain of B6 mice.11 The phenotype is one of focal alopecia pro- Conference Comment: The conference gressing to ulcerative dermatitis and description focused on the numerous empty scarring, and is attributed to polymorphism and/or keratin filled, malformed, ectatic hair in alcohol dehydrogenase (Adh4) and follicles as well as disorganization and differential expression of epithelial retinol hyperplasia of the sebaceous glands and dehydrogenase (DHRS9), leading to the ectatic sebaceous gland ducts. The impaired removal of excess retinol. Yet moderator was careful to point out that dilated sebaceous gland ducts should not be confused with dilated hair follicles as both The placode grows down into the are present in this case. Participants also mesenchyme which is followed by noted the presence of dilated apocrine differentiation of the follicular mesenchyme, glands, malformed hair bulbs and shrunken, and formation of the dermal papilla and fragmented, malformed and hypereo- connective tissue sheath, which leads to sinophilic hair shafts, with absence of formation of the hair bulb. The hair bulb is normal hair shaft architecture, which led to responsible for formation of the hair shaft. interpretation as a form of congenital When the mesenchymal cells of the dermal hypotrichosis. papilla become enclosed by keratinocytes, formation of the hair shaft begins. Hair Although uncommon, a similar condition shaft formation is accomplished by the has been reported previously in white tailed matrix keratinocytes of the hair bulb. Hair deer. In the other reported case, hair follicle shafts are composed of a cortex, which is density was normal, follicles were ectatic covered by a cuticle protecting the hair from and either empty or contained keratin debris damage, and many hair shafts have a and hair shaft fragments, and apocrine ducts pigmented medulla. Surrounding the hair were dilated and hair bulbs were abnormal, shaft is the inner root sheath, which similar to what was seen in this case. In that disappears at the level of the follicular case there was normal hair present on the infundibulum. The outer root sheath forms ventral thorax and sebaceous gland at the same time as the inner root sheath and hypertrophy and hyperplasia was variably hair follicle, but is not derived from matrix present. There was also mild epidermal keratinocytes. Downgrowth of the outer hyperplasia and hyperpigmentation, similar root sheath pushes the hair bulb toward the to what is seen in this case. The authors of subcutis while matrix keratinocytes are that manuscript went on to discuss the types producing the hair shaft and inner root of congenital hypotrichosis described in sheath, which grow toward the skin surface. cattle including forms which are lethal, As mentioned above by the contributor, hair forms associated with dental abnormalities follicle dysplasias, which involve defects in and viable hypo-trichosis, which shares the hair follicle and shaft, are often many similarities with this case.12 Viable differentiated from the alopecic conditions hypotrichosis is reported to affect Guernsey, where the hair follicle appears normal, but Jersey, Holstein and Hereford cattle with an the shaft itself is abnormal. Additionally, it autosomal recessive mode of inheritance is important to differentiate between resulting in dysplastic hair follicles that alopecic conditions with a decreased number don’t produce

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