Cases 68a and b

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1 Epidermal maturation Nathan C. Walk, M.D.

2 Cases 68a and b

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9 Porokeratosis Clinical variants: (classification inconsistent) Porokeratosis of Mibelli Disseminated superficial porokeratosis Disseminated superficial actinic porokeratosis Linear porokeratosis Porokeratosis plantaris palmaris et disseminate Pathogenesis? Mutant clone of keratinocytes

10 Histology: Cornoid lamella Thin column of parakeratotic cells with an absent or decreased granular layer Vacuolated or dyskeratotic cells in the spinous layer May be associated with eccrine ducts or hair follicles Note: must take biopsy at edge of peripheral rim to see cornoid lamella Presence of significant cornoid lamella at both ends of a biopsy with abnormal keratinization (usually compact hyper) is diagnostic of porokeratosis. Cornoid lamella alone can be seen in other inflammatory skin conditions or tumors.

11 Case 69

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15 Ichthyosis vulgaris Most common 1/250 Deficiency of profilaggrin Autosomal dominant Histology: Hyperkeratosis Diminished granular layer Thinned epidermis, diminished rete pattern Small skip areas 1 or 2 cells wide in which granular cell is totally absent is extremely helpful usually does not occur in other ichthyoses or normal skin.

16 Distinguishing micro features of ichthyoses Ichthyoses all have hyperkeratosis Vulgaris AD decreased profilaggrin Decreased granular layer Thin epidermis, diminished rete Follicular plugging X-linked steroid sulfatase deficiency Normal/thickened granular layer Acanthosis Lamellar Ar transglutaminase-1 mutation Mild acanthosis, psoriasiform hyperplasia, extensive hyperkeratosis Nonbullous CIE Ar Same as lamellar, but + parakeratosis, looks a lot like psoriasis w/ decreased Granular layer below parakeratosis, + neutrophils Bullous CIE AD K1 and K10 mutations Epidermolytic hyperkeratosis

17 Case 70

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21 Lamellar ichthyosis Autosomal recessive Present at birth erythroderma + scaling May be a cause of collodion baby Some with mutation in transglutaminase-1 gene Overlap with nonbullous CIE (+ erythroderma, finer scale) Histology: Moderate to severe compact hyperkeratosis Retains granular later Mild acanthosis Psoriasiform hyperplasia

22 Distinguishing micro features of ichthyoses Ichthyoses all have hyperkeratosis Vulgaris AD decreased profilaggrin Decreased granular layer Thin epidermis, diminished rete Follicular plugging X-linked steroid sulfatase deficiency Normal/thickened granular layer Acanthosis Lamellar Ar transglutaminase-1 mutation Mild acanthosis, psoriasiform hyperplasia, extensive hyperkeratosis Nonbullous CIE Ar Same as lamellar, but + parakeratosis, looks a lot like psoriasis w/ decr. Granular layer below parakeratosis, + neutrophils Bullous CIE AD K1 and K10 mutations Epidermolytic hyperkeratosis

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24 Case 71

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29 Darier s disease Autosomal dominant disorder of keratinization Hyperkeratotic papules that coalesce Seborrheic areas, onset in childhood usually ATP2A2 calcium pump in Endoplasmic Reticulum Histology: Acantholytic kyskeratosis Compact hyperkeratosis Parakeratosis Corps grains Corps ronds Acantholytic keratinocytes Suprabasilar clefts only basal keratinocytes remain attached producing villi

30 Acantholytic dyskeratosis DDx: Darier s - generalized Grover s - transient Actinic keratosis - incidental Warty dyskeratoma Variant of epidermal nevus Pl Palmarplantar l rare form of fk keratoderma

31 Grover s 4 variants *Darier-like Hailey-Hailey-likelike *Pemphigus vularis-like like Spongiotic Grover s looks distinct i clinically, i ll but histologically i ll may mimic i any of the above helpful hints: + eosinophils Small size of lesions may be only a few rete + spongiosis Can use DIF to differentiate from pemphigus

32 Case 72

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36 Warty dyskeratoma Hyperkeratotic, umbilicated, persistent nodule on sun-exposed skin of H/N of adults Most often solitary? Etiology Follicular derived Histology: Deeply penetrating crateriform lesion Keratinous debris, often a/w hair follicle Corps ronds and grains Deeper epithelium shows: Marked acantholysis and suprabasal villi

37 Case73

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42 Hailey-Hailey Autosomal dominant genodermatotis ATP2C1 calcium pump localized in Golgi Vesicles or bullae that erode Intertriginous areas aggravated by heat, friction, infection Histology: Acantholysis affecting stratum spinosum dilapidated brick wall appearance Hair follicles normal Keratinocytes eosinophilic due to clumped tonofilaments

43 Hailey-Hailey compare with: Pemphigus vulgaris H-H H features: Acantholysis is multifocal, cytoplasmic eosinophilia, no eosinophils, absence of involvement of hair follicles Darier s Has corps ronds and grains, less acantholysis

44 Cases 74a and b

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51 Epidermolytic hyperkeratosis This histologic pattern may be seen in a number of different clinical settings: Bullous ichthyosis Epidermal nevus variant Palmoplantar keratoderma variant Epidermolytic acanthoma Incidental Rare variant of solar keratosis Nevoid follicular epidermolytic hyperkeratosis Epidermolytic leukoplakia

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53 Unknowns

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