1. Skin Pathology IV

2. Acne Vulgaris More severe in Males. Can be caused by: Drugs
Occupational Exposures
Cosmetics
Tropical Climates
Types:
Non-Inflammatory:
Open Comedones: Small, follicular papules containing a central, black keratin plug (blackheads)
Closed Comedones: Follicular papules without a visible central plug.
Inflammatory:
Erythematous
Propionibacterium Acnes: Administration of Antibiotics to individuals with inflammatory acne.
13-cis-retinoic acid: a synthetic Vitamin A derivative that has strong anti-sebaceous action and shows remarkable improvement.
Causes Birth Defects.

3. Seborrheic Keratosis Common Epidermal Tumors
Round, Flat, Coin-Like “tan, waxy plaques” that vary in diameter.
Genetic: FGFR3, Receptor Tyrosine Kinase
Histology:
Hyperkeratosis
Keratin-Filled Horn Cysts
Invagination Cysts of Keratin
Variable melanin pigmentation.

4. Acanthosis Nigricans
Thickened, Hyperpigmented Skin with a “velvet-like texture”
Appears in flexural areas.
Genetic: FGFR3, Receptor Tyrosine Kinase
80% are benign.
20% are malignant  gastrointestinal adenocarcinoma

5. Dermatofibroma Also called Benign Fibrous Histiocytoma
Usually a history of previous trauma.
Firm, Tan-Brown Papules, can be >1 cm
Dimple-Sign: When sqeezed from edges, center dimples
Histology:
Pseudoepitheliomatous Hyperplasia: overlying the lesion
Epidermis has hyperpigmented Basal Layer
Peripheral Collagen Trapping – at edge of lesion
Usually stays confined to the Dermis
Stains:
Factor XIIIa – Positive
CD34 - Negative

6. Dermatofibroma Sacoma Protuberans (DFSP)
Same general features as a Dermatofibroma.
DIFFERENCEs:
DFSP shows vacuoles or “fat trapping” on histology, which is clear. Where Dermatofibroma has “Collagen Trapping”, which is pink.
DFSP is:
Factor XIIIa Negative
CD34 Positive
CD34 Positive

7. Actinic Keratosis Caused by UV Light
Considered Pre-Cancerous  Squamous Cell Carcinoma
Tan-Brown or Pink-Red Lesions with a rough, yellowish-brown or white scale.
Can also look horned.
Histology:
Hyperkeratosis with Hyperplasia
Dysplasia of the Epidermal Basal Layer (from the bottom, upward)
Not Full Thickness!!!
Full Thickness = Squamous Cell Carcinoma in situ
Elastosis: The superficial epidermis contains thickened, blue-gray elastic fibers caused by UV-damaged Fibroblasts.
Normal skin appendage areas.

8. Keratoacanthoma
Arises from hair follicles in sun exposed areas in >50 year olds
Description:
Dome-Shaped, Crusty Lesions with Central, Keratin-Filled Crater that mimics a well-differentiated squamous cell carcinoma.
Histology:
Volcano
Tx:
Can spontaneously regress in 3-4 months
Should be treated as though it is a Squamous Cell Carcinoma

9. Squamous Cell Carcinoma
Cause:
DNA Damage from UV Light Exposure
Immunosuppression
Squamous Cell Carcinoma in situ:
Not invaded through the Basement Membrane.
Appear as sharply defined, red, scaling plaques.
Invasive Lesions:
Nodular, Hyperkeratotic Scales
Ulceration/Necrosis
Invade the Basement Membrane
Histology:
Variable degrees of differentiation.
Keratin Pearls
May need immunostains to confirm the lineage.

10. Basal Cell Carcinoma Cause:
Mutations that activate the Hedgehog Pathway.
Sun-Exposed sites in fair-skinned, elderly patients.
Epidemiology
Locally aggressive cutaneous tumor.
Most common invasive cancer in humans.
Slow-Growing, Rarely Metastasize
Histology:
Variable types
Pearly Papules with Telangiectasis (dilated blood vessels)
Can have local invasion of bone or facial sinuses after many years of neglect = Rodent Ulcers
Blue “basaloid” Cells.
Peripheral Palisades
Clefting: separation of tumor from surrounding stroma
Embedded in mucinous Basal Cell Matrix = Basal Cell Stroma

11. Nevoid Basal Cell Carcinoma Syndrome
Rare, Genetic Syndrome
Causes Basal Cell Carcinomas at a very young age (12 years old)
Gene: PTCH
Tumor Suppressor Gene
Born with a germline loss of function mutation in one PTCH Allele.
Second Hit is required, by chance, causing early carcinoma formation.

13. Treatment: 13-cis-retinoic acid. Side Effects: Serious birth defects
Acne Vulgaris
Treatment: 13-cis-retinoic acid.
Side Effects: Serious birth defects

15. Treatment: 13-cis-retinoic acid. Side Effects: Serious birth defects
Acne Vulgaris
Treatment: 13-cis-retinoic acid.
Side Effects: Serious birth defects

17. Tan-Brown Waxy Plaques that vary in diameter.
Seborrheic Keratosis
Tan-Brown Waxy Plaques that vary in diameter.

19. Sebhorrheic Keratosis
Tan-Brown Waxy Plaques that vary in diameter.

21. Sebhorrheic Keratosis
Invaginations of Keratin (Invagination Cysts)
Horn Cysts

23. Sebhorrheic Keratosis
Invaginations of Keratin (Invagination Cysts)
Horn Cysts

25. Velvet-Like, Thickened, Hyperpigmented Skin Flexural Areas
Acanthosis Nigricans
Velvet-Like, Thickened, Hyperpigmented Skin
Flexural Areas

27. Velvet-Like, Thickened, Hyperpigmented Skin Flexural Areas
Acanthosis Nigricans
Velvet-Like, Thickened, Hyperpigmented Skin
Flexural Areas

29. Dimple Sign: when squeezed from edges, center dimples.
Dermatofibroma
Dimple Sign: when squeezed from edges, center dimples.
Factor XIIIa Positive
CD34 Negative

31. Dimple Sign: when squeezed from edges, center dimples.
Dermatofibroma
Dimple Sign: when squeezed from edges, center dimples.
Factor XIIIa Positive
CD34 Negative

33. Peripheral Collagen Trapping Factor XIIIa Positive CD34 Negative
Dermatofibroma
Peripheral Collagen Trapping
Factor XIIIa Positive
CD34 Negative

35. Dermatofibroma Sarcoma Protuberans (DFSP)
Vacuoles: “Fat Trapping”
Not Collagen Trapping like Dermatofibromas

37. Dermatofibroma Sarcoma Protuberans
CD34 + Stain
Factor XIIIa Negative

39. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Tan-Brown or Pink-Red lesions with scales/horns.

41. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Tan-Brown or Pink-Red lesions with scales/horns.

43. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Tan-Brown or Pink-Red lesions with scales/horns.

45. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Tan-Brown or Pink-Red lesions with scales/horns.

47. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Not Full Thickness
Hyperkeratosis, Hyperplasia, Parakeratosis,
Dyspasia of Basal Cell Layer
Elastosis

49. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Not Full Thickness
Hyperkeratosis, Hyperplasia, Parakeratosis,
Dyspasia of Basal Cell Layer
Elastosis, Normal Skin Appendage Areas

51. Actinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Not Full Thickness
Hyperkeratosis, Hyperplasia, Parakeratosis,
Dyspasia of Basal Cell Layer
Elastosis

53. Acinic Keratosis UV  Pre-Cancerous  Squamous Cell Carcinoma
Not Full Thickness
Hyperkeratosis, Hyperplasia, Parakeratosis,
Dyspasia of Basal Cell Layer
Elastosis

55. Volcano Should be treated as though it is a Squamous Cell Carcinoma
Keratoancthoma
Volcano
Should be treated as though it is a Squamous Cell Carcinoma

57. Squamous Cell Carcinoma
In Situ
Non-Nodular
Sharply-Defined, Red, Scaling Plaques

59. Squamous Cell Carcinoma
Invasive
Nodular
Hyperkeratotic Scales, Ulcerations

61. Squamous Cell Carcinoma
Keratin Pearls
Has no invaded the Basement Membrane
Full-Thickness Dysplasia – In Situ

63. Blue “Basaloid” Cells Peripheral Palisades Clefting
Basal Cell Carcinoma
Blue “Basaloid” Cells
Peripheral Palisades
Clefting

65. Squamous Cell Carcinoma
Keratin Pearls
Invaded Basement Membrane
Invasive

67. Squamous Cell Carcinoma
Keratin Pearls
Invaded Basement Membrane
Invasive

69. Volcano Should be treated as though it is a Squamous Cell Carcinoma
Keratoacanthoma
Volcano
Should be treated as though it is a Squamous Cell Carcinoma

71. Squamous Cell Carcinoma
Keratin Pearls
Invaded Basement Membrane
Invasive
Poorly Differentiated

73. Blue “Basaloid” Cells Peripheral Palisades Clefting
Basal Cell Carcinoma
Blue “Basaloid” Cells
Peripheral Palisades
Clefting

75. Pearly Papules containing dilated Sub-Epidermal Blood Vessels.
Basal Cell Carcinoma
Pearly Papules containing dilated Sub-Epidermal Blood Vessels.
Can have ulcerations.

77. Squamous Cell Carcinoma
Keratin Pearls
Invaded Basement Membrane
Invasive

79. Squamous Cell Carcinoma
Keratin Pearls
Has no invaded the Basement Membrane
Full-Thickness Dysplasia – In Situ