skin pathology

skin

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Normal

epidermis
- stratum corneum: keratin layer
- stratum granulosum: granular cells
- stratum spinosum: keratinocytes, langerhans cells
- stratum basalis: basal cells, melanocytes
dermis
- vessels, nerves, pacinian corpuscle
- collagen stroma
- adnexa: eccrine, apocrine, sebaceous, pilar muscle
- lymphocytes, mast cells
hypodermis
- fat
adnexa
- hair shafts, follicles
- glands and ducts: eccrine, apocrine, sebaceous
- nail

Ddx

inflammation
- folliculitis
- abscess
- fungus
- dermatitis
  - perivascular
    - minimal epidermal changes
    - interface dermatitis
    - epidermal spongiosis
      - spongiotic dermatitis
      - incontinentia pigmenti
    - psoriasiform dermatitis
  - nodular and diffuse
    - neutrophils
      - Sweet syndrome
      - pyoderma gangrenosum
    - eosinophils
      - eosinophilic cellulitis
      - scabies
    - histiocytes
      - xanthogranuloma
      - reticulohistiocytic granuloma
    - granulomas
      - palisading and necrobiotic
        granuloma annulare
        necrobiosis lipoidica
        rheumatoid nodule
        necrobiotic xanthogranuloma
      - infectious
        leprosy
        lupus vulgaris
        fungus
        leishmaniasis
      - other
        sarcoidosis
        foreign body granuloma
- vasculitis
  - leukocytoclastic vasculitis
  - erythema induratum
  - polyarteritis nodosa
  - granuloma faciale
  - superficial migratory thrombophlebitis
- scleroderma
  - morphea
- panniculitis
  - erythema nodosum
  - fat necrosis
melanocytic
- melanoma
  - superficial spreading melanoma
  - nodular melanoma
  - lentigo maligna
  - acral lentiginous melanoma
  - desmoplastic melanoma
  - childhood melanoma
  - nevoid melanoma
  - melanoma arising from blue nevus
  - melanoma arising in giant congenital nevi
  - regressing melanoma
  - spindle cell melanoma
  - clear cell sarcoma
- benign melanocytic nevus
  - by layer
    - junctional nevus (junction only)
    - compound nevus (junction and dermal)
    - intradermal nevus (dermal only)
  - dysplastic nevus
  - blue nevus
  - Spitz nevus
  - acquired nevus
  - congenital nevus
  - giant pigmented nevus
  - intramucosal nevus
  - recurrent nevus
- nevus of Ito
- Mongolian spot
- solar lentigo
- melanotic macule
epidermal
- SCC
- SCC in situ
- BCC
- verruca
- actinic keratosis
- seborrheic keratosis
- keratoacanthoma
- other acanthomas
  - epidermolytic acanthoma
  - warty dyskeratoma
  - acantholytic acanthoma
  - solar lentigo
  - melanoacanthoma
  - clear cell acanthoma
  - large cell acanthoma
  - lichen planus like keratosis
- hyperplasia
- keratoses
  - hyperkeratosis
  - parakeratosis
  - dyskeratosis
- molluscum contagiosum
- lichen simplex chronicus
acantholytic
- pemphigus
- Darier disease
- Grover disease
- Hailey Hailey disease
- HSV
blistering
- bullous pemphigoid
- dermatitis herpetiformis
- porphyria cutanea tarda
- subcorneal pustular dermatosis
- HSV
cystic
- abscess
- epidermoid inclusion cyst
- dermoid cyst
- pilar cyst
- cystic BCC
adnexal
- Apocrine/eccrine
  - tubular carcinoma
  - tubular adenoma
  - porocarcinoma
  - poroma
  - spiradenocarcinoma
  - spiradenoma
  - syringoma
  - syringofibroadenoma
  - syringocystadenoma papilliferum
  - hidradenocarcinoma
  - hidradenoma
  - hidradenoma papilliferum
  - hidrocystoma
  - cylindroma
  - malignant mixed tumor
  - mixed tumor
  - microcystic adnexal carcinoma
  - mucinous carcinoma
  - digital papillary carcinoma
  - adenoid cystic carcinoma
  - apocrine carcinoma
  - Paget disease
- Follicular
  - folliculitis
  - pilomatrical carcinoma
  - pilomatricoma
  - pilar sheath acanthoma
  - pilar cyst
  - proliferating tricholemmal tumor
  - trichoepithelioma
  - tricholemmoma
  - trichofolliculoma
  - fibrofolliculoma
  - tumor of the follicular infundibulum
- Sebaceous
  - sebaceous carcinoma
  - sebaceous adenoma
  - sebaceoma
  - cystic sebaceous tumor
  - nevus sebaceus
vascular
- Kaposi sarcoma
- angiosarcoma
- hemangioma
- lymphangioma
- pyogenic granuloma
- thrombogenic vasculopathy
spindle cell
hematopoietic
- mycosis fungoides
- Sezary syndrome
- mastocytosis
- T lymphoma
- B lymphoma
- myeloid leukemia
- Langerhans cell histiocytosis
- urticaria pigmentosa
other
- keloid
- Merkel cell carcinoma