Essences of clinical medicine.

Cardiology / 循環器科

Pulmonology/ 呼吸器科

Gastroenterology / 消化器科

Endocrinology / 内分泌科

Nephrology / 腎臓科

Hematology / 血液科

Rheumatology / リウマチ科

Infectious Diseases / 感染症科

Neurology / 神経科

Psychiatry / 精神科

Ophthalmology / 眼科

Otolaryngology / 耳鼻咽喉科

Dermatology / 皮膚科

Pigmentation Disease / 色素疾患

Freckle / 雀卵斑

• Pathology
  • Enhanced pigment production/transfer of melanocytes
• Subjective
  • Small brown macules on face
  • Darken/Fade in summer/winter: Degree of pigmentation depends on sunlight
• Assessment
  • Suspect neurofibromatosis if >=6 larger macules (cafe-au-lait spot)

Lentigo / 黒子

• Pathology
  • Benign localized hyperplasia of melanocytes
• Subjective
  • Oval tan-brown macule/patch
• Objective
  • [Patho] Linear melanocytic hyperplasia above basement membrane

Melanocytic Nevus / 色素性母斑

• Pathology
  • Benign neoplasm of melanocytes
  • Mostly due to activating mutation in RAS signaling pathway
• Subjective
  • Tan to brown, uniformly pigmented, well-defined small macules
• Objective
  • [Patho] Nests or cords of nevus cells: Progress from dermoepidermal junction (junctional) to dermis (compound) and loss in epidermis (intradermal)
• Assessment
  • [Variant] Congenital nevus: Large variants have increased melanoma risk
  • [Variant] Blue nevus: Black-blue nodule
  • [Variant] Spitz nevus: Red-pink nodule
  • [Variant] Halo nevus: Immune response against nevus cells
  • [Variant] Dysplastic nevus: Potential marker or precursor of melanoma
  • [Related] Nevus of Ota: Blue discoloration in periorbital region
  • [Related] Mongolian spot: Blue discoloration in lumbosacral region from birth

Melanoma / 悪性黒色腫

• Pathology
  • Malignant neoplasm of melanocytes, related to UV light
  • Driver mutations in CDKN2A, RAF/RAS, TERT promoter
• Subjective
  • Macules characterized by “ABCDE”: Asymmetry, Border irregularity, Color variegation, Diameter enlargement, Evolution
• Objective
  • [Dermoscopy] Parallel ridge pattern, atypical pigment network: Extensive melanocyte proliferation
  • [Patho] Nests of atypical cells with enlarged nuclei, prominent nucleoli, increased mitosis: Initial radial growth, later vertical growth
• Assessment
  • [Type] Acral lentiginous melanoma: Unrelated to sun exposure, most common in Asian/Africa
  • [Type] Superficial spreading melanoma: Related to sun exposure, most common in Western world
  • [Type] Nodular melanoma: Vertical growth
  • [Type] Lentigo maligna melanoma: indolent growth over decades
  • [Staging] T: By tumor thickness
• Plan
  • Surgical resection, sentinel lymph node biopsy, lymph node dissection: Before metastasis
  • [Immune checkpoint inhibitor] Anti-CTLA4, anti-PD1: Melanoma is inherently immunogenic
  • [Target therapy] BRAF inhibitor, MEK inhibitor: Inhibit RAS signaling pathway

Vitiligo Vulgaris / 尋常性白斑

• Pathology
  • Pigment loss due to melanocyte loss, may be due to autoimmune melanocyte destruction or nerve innervation abnormality
• Subjective
  • Well-demarcated zone of pigment loss
• Assessment
  • [Type] Segmental: Following dermatome
  • [Type] Non-segmental: Not following dermatome
• Plan
  • Topical steroid
  • UVB

Benign Epithelial Tumor / 良性上皮腫瘍

Seborrheic Keratosis / 脂漏性角化症

• Pathology
  • Benign proliferation of keratinocytes (basal cell, squamous cell)
  • Frequent in middle-aged or older individuals
  • Often due to activating mutation in FGFR3
• Subjective
  • Well-demarcated, tan to dark brown plaque with granular surface
• Objective
  • [Patho] Basaloid cells with melanin pigmentation, keratin-filled cyst (horn cyst)
• Assessment
  • Suspect gastrointestinal malignancy if suddenly appear in large numbers (Leser-Trelat sign)

Acanthosis Nigricans / 黒色表皮腫

• Pathology
  • Hyperplasia of keratinocytes
  • Causes include inheritance, obesity, diabetes, malignancy (especially gastrointestinal)
  • Often due to FGFR3 mutation (familial), IGF1R activation (diabetes), EGFR activation (malignancy)
• Subjective
  • Thickened hyperpigmented rough skin in flexural areas
• Objective
  • [Patho] Papillomatosis, hyperkeratosis, hyperpigmentation

Fibroepithelial Polyp / 軟性線維腫

• Pathology
  • Benign skin hyperplasia (skin tag)
• Subjective
  • Soft and flesh-colored tumor, often with stalk
• Objective
  • [Patho] Fibrovascular core covered by benign epithelium

Epithelial Cyst / 表皮囊腫

• Pathology
  • Invagination and cystic expansion of epidermis or hair follicle
• Subjective
  • Skin-colored, dome-shaped nodule
  • Painful if inflammed
• Objective
  • [Patho] Keratin-filled cyst with epidermal wall

Appendage Tumor / 付属器腫瘍

• Pathology
  • Neoplasm arising from or differentiating toward skin appendage, mostly benign
• Objective
  • [Patho] Pilomatrixoma: Resembling germinal portion of hair bulb
  • [Patho] Trichoepithelioma: Resembling primitive hair follicle
  • [Patho] Syringoma, eccrine poroma: Resembling eccrine gland
  • [Patho] Apocrine carcinoma: Resembling apocrine gland
  • [Patho] Cylindroma: Resembling eccrine/apocrine duct
  • [Patho] Sebaceous adenoma: Resembling sebaceous gland

Malignant Epithelial Tumor / 悪性上皮腫瘍

Actinic Keratosis / 日光角化症

• Pathology
  • Precancerous neoplasm of keratinocytes due to UV light, may progress to SCC
• Subjective
  • Tan-brown or red macule with scale or horn
• Objective
  • [Patho] Hyperplasia of atypical basal cell, parakeratosis, elastosis
• Plan
  • Surgical resection, freezing
  • Topical imiquimod: Activate TLR and innate immune response

Extramammary Paget Disease / 乳房外Paget病

• Pathology
  • Malignant neoplasm of Paget cell within epidermis (intraepidermal adenocarcinoma)
• Subjective
  • Large erythematous (and erosive) patch on external genitalia
• Objective
  • [Patho] Large cell with clear cytoplasm within epidermis: Paget cell
• Plan
  • Wide excision

Squamous Cell Carcinoma / 有棘細胞癌

• Pathology
  • Malignant neoplasm of keratinocytes due to UV light (other causes: immunosuppression, chronic ulcer, burn scar)
  • Mutation in TP53, and RAS and NOTCH signaling pathway
• Subjective
  • Red nodule/plaque with scale and/or ulceration
• Objective
  • [Patho] Atypical cells with variable differentiation, involve full-thickness epidermis and invade dermis
• Assessment
  • [Variant] Keratoacanthoma: Dome-shaped tumor with central keratinous plug, well-differentiated SCC that often spontaneously regress
• Plan
  • Surgical resection, radiotherapy

Basal Cell Carcinoma / 基底細胞癌

• Pathology
  • Malignant neoplasm of basaloid cell, related to UV light
  • Locally aggressive but slow growing and rarely metastasize
  • Due to mutation in Hedgehog signaling pathway (often PTCH)
• Subjective
  • Brown to black pearly papules/nodules, sometimes with ulcer
• Objective
  • [Dermoscopy] Telangiectasias, multifocal or nodular growth
  • [Patho] Nests of basaloid cells, peripheral palisading, artificial cleft
• Plan
  • Surgical resection

Dermal Tumor / 真皮腫瘍

Dermatofibroma / 皮膚線維腫

• Pathology
  • Benign neoplasm of fibroblast and histiocyte
• Subjective
  • Tan to brown firm papule/nodule
• Objective
  • [Patho] Benign spindle cells in dermis, overlying epidermal hyperplasia

Dermatofibrosarcoma Protuberans / 隆起性皮膚線維肉腫

• Pathology
  • Malignant neoplasm of fibroblast
  • Locally aggressive but slow growing and rarely metastasize
  • Due to COL1A1-PDGFB translocation, lead to increased PDGFβ secretion
• Subjective
  • Firm protuberant nodule
• Objective
  • [Patho] Storiform fibroblast, often extend to subcutaneous fat
• Plan
  • Surgical resection

Mycosis Fungoides / 菌状息肉症

• Pathology
  • Malignant neoplasm of CD4+ T-helper cells involving skin (cutaneous T cell lymphoma)
  • Localized to skin initially, may evolve to systemic lymphoma after years
• Subjective
  • Multiple erythematous patches: Erythematous stage
  • Red to brown scaling plaques: Plaque stage
  • Brown ulcerated nodule: Tumor stage
• Objective
  • [Patho] CD4+ lymphocyte infiltration, band-like in dermis, Pautrier microabscess in epidermis
• Plan
  • Topical steroid, UV light: For early stage
  • Systemic chemotherapy: For advanced stage

Mastocytosis / 肥満細胞症

• Pathology
  • Benign proliferation of mast cells in skin (urticaria pigmentosa)
  • Due to mutation in KIT (and also PDGFRA)
• Subjective
  • Multiple red-brown patches/nodules, mainly in children
  • Localized edema when lesion rubbed (Darier sign): Histamine release from mast cells
  • Wheals, pruritus, flush triggered by food or temperature change: Histamine release from mast cells
• Objective
  • [Patho] Proliferation of mast cells in dermis
• Assessment
  • Spontaneous resolve in children

Vascular Tumor / 血管腫瘍

Vascular Ectasia / 血管拡張症

• Pathology
  • Dilatations of capillaries/venules/arterioles, not neoplasm
• Subjective
  • [Nevus flammeus] Pink/purple patch on head/neck in infant, regress spontaneously (except port wine stain which persists)
  • [Spider telangiectasia] Radial pulsatile lesion, associated with hyper-estrogenic state
• Assessment
  • [Association] Sturge-Weber syndrome: Vascular ectasia of face (port wine stain), leptomenings (intellectual disability, hemiplegia), choroid plexus (glaucoma), due to GNAS mutation
  • [Association] Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease): Multiple telangiectasias on skin/mucosa, causing recurrent epistaxis

Hemangioma / 血管腫

• Pathology
  • Benign neoplasm of endothelial cell with blood-filled vessels
• Subjective
  • Blood-rich tumor on skin/mucosa or viscera
• Assessment
  • [Capillary hemangioma] Common, with thin-walled capillaries
  • [Cavernous hemangioma] Infiltrative, with cavernous vascular space, associated with von Hippel-Lindau disease
  • [Juvenile hemangioma] Common in newborn, mostly regress
  • [Pyogenic granuloma] Rapidly growing pedunculated lesion, easily bleeding

Lymphangioma / リンパ管腫

• Pathology
  • Benign neoplasm of lymphatic endothelial cell
• Subjective
  • Tumor on head/neck/axilla
• Assessment
  • [Capillary lymphangioma]
  • [Cavernous lymphangioma] Associated with Turner syndrome

Glomus Tumor / グロムス腫瘍

• Pathology
  • Benign neoplasm of smooth muscle cell of glomus body
• Subjective
  • Painful tumor on distal digit (often under fingernails)

Bacillary Angiomatosis / 細菌性血管腫症

• Pathology
  • Vascular proliferation in immunocompromised hosts due to Bartonella infection (produce HIF and induce vascular proliferation
• Subjective
  • Red papules/nodules

Kaposi Sarcoma / Kaposi肉腫

• Pathology
  • Borderline neoplasm of endothelial cell, caused by HHV8 infection and immunosuppression (AIDS, transplant, aging)
  • HHV8 infect endothelial cell and stimulate growth
• Subjective
  • Red-purple patches → plaques → nodules
• Objective
  • [Patho] Irregular vascular space, plump spindle cells, interspersed erythrocytes and mononuclear cells
  • [PCR] HHV8 (+)
• Assessment
  • [Type] Classic KS: In older man, not HIV-related
  • [Type] Endemic African KS: In younger African, not HIV-related
  • [Type] Transplant-associated KS: In organ transplant recipient under immunosuppression
  • [Type] AIDS-associated KS: Most common, AIDS-defining illness
• Plan
  • Surgery, radiotherapy, chemotherapy
  • Withdrawal of immunosuppression: Transplant-associated
  • Antiretroviral therapy: AIDS-associated

Angiosarcoma / 血管肉腫

• Pathology
  • Malignant neoplasm of endothelial cell, idiopathic or related to lymphedema after mastectomy, radiation, trauma
• Subjective
  • Initial red papules, later red-tan nodules with blurring margin, bleeding and ulceration: Often in head/neck of elderly
• Objective
  • [Patho] Irregular vascular space, atypical endothelial cells (various degree of differentiation)
• Plan
  • Surgery, radiotherapy, chemotherapy

Acute Inflammatory Dermatosis / 急性炎症性皮膚疾患

Urticaria / じんま疹

• Pathology
  • Dermal microvascular hyperpermeability due to localized mast cell degranulation of histamine
  • Causes include antigens, exercise, temperature change, stress
• Subjective
  • Pruritic edematous plaques (wheals)
  • Develop and fade within hours, episode for days to months
• Objective
  • [Patho] Edema and dilated vessels in superficial dermis
• Assessment
  • [Related] Angioedema: Edema of deeper dermis and subcutaneous fat
  • [Related] C1 inhibitor deficiency: Hereditary angioedema due to excessive bradykinin production
• Plan
  • Antihistamine
  • Avoid causative agents

Acute Eczematous Dermatitis / 急性湿疹性皮膚炎

• Pathology
  • Acute inflammatory dermatosis, often due to immune reaction mediated by CD4+ T lymphocytes
  • Causes include external antigen (plant, metal), internal antigen (food, drug), predisposition (atopy)
• Subjective
  • Erythematous pruritic patch/plaque, sometimes with papules/vesicles/crusts/scales: Acute phase
  • Lichenification, pigmentation: Chronic phase
  • [Contact dermatitis] Lesion coincides with contact region
  • [Atopic dermatitis] Recurrent and chronic course, symmetrical distribution
• Objective
  • [Patho] Spongiosis (epidermal edema), acanthosis, hyperkeratosis, inflammatory cell infiltration
  • [Contact dermatitis] Patch test positive
  • [Atopic dermatitis] IgE↑, eosinophil↑
• Assessment
  • [Clinical] Contact dermatitis: Due to contact of causative agents (allergic/irritant)
  • [Clinical] Atopic dermatitis: Due to atopy and impaired skin barrier function
• Plan
  • Topical steroid
  • [Contact dermatitis] Avoid causative agents
  • [Atopic dermatitis] Tacrolimus ointment (calcineurin inhibitor): Inhibit cytokine release from T cells
  • [Atopic dermatitis] JAK inhibitor: Inhibit signal transduction in immune cells

Erythema Multiforme / 多形紅斑

• Pathology
  • Hypersensitivity reaction of skin, due to keratinocyte injury mediated by CD8+ T lymphocytes
  • Causes include infection (herpes, mycoplasma), drug (sulfonamide, carbamazepine), cancer, collagen disease
• Subjective
  • Multiple target-like erythematous macules/plaques
  • [SJS] Extensive erythema with blister/erosion on skin/mucosa, febrile
  • [TEN] Extensive erythema with necrosis/sloughing of skin/mucosa (burn-like), febrile
• Objective
  • [Patho] Keratinocyte necrosis, lymphocyte infiltrates along dermoepidermal junction
  • [Patho, SJS] Keratinocyte necrosis in cluster
  • [Patho, TEN] Keratinocyte necrosis in layer
• Assessment
  • [Variant] Stevens-Johnson syndrome: Involvement < 10% BSA
  • [Variant] Toxic epidermal necrolysis: Involvement > 10% BSA
  • [Variant] Drug-induced hypersensitivity syndrome: With liver dysfunction, anti-HHV6 antibody↑
• Plan
  • Topical steroid, antihistamine
  • [SJS, TEN] Terminate causative drug, systemic steroid

Acute Febrile Neutrophilic Dermatosis / 急性熱性好中球性皮膚症

• Pathology
  • Tender erythematous nodule with fever, related to hematologic or solid malignancy
  • Also called Sweet’s disease
• Subjective
  • Tender erythematous nodule/plaque, on face/upper-limbs
  • Often with high fever, arthralgia
• Objective
  • [Patho] Neutrophilic infiltration in dermis, edema of dermal papilla
  • [Blood] Neutrophil↑, CRP↑
• Plan
  • NSAID, corticosteroid

Pyoderma Gangrenosum / 壊疽性膿皮症

• Pathology
  • Noninfectious necrotic ulcer, related to systemic disease (inflammatory bowel disease, hematologic malignancy, rheumatoid arthritis)
• Subjective
  • Necrotic ulcer with violaceous elevated edge
• Objective
  • [Patho] Neutrophilic infiltration in dermis

Chronic Inflammatory Dermatosis / 慢性炎症性皮膚疾患

Seborrheic Dermatitis / 脂漏性皮膚炎

• Pathology
  • Chronic inflammatory dermatosis involving regions with high density of sebaceous glands
  • Causes related to sebum production and Malassezia colonization
• Subjective
  • Erythematous greasy macules/patches with scales and crusts
• Objective
  • [Patho] Spongiosis, acanthosis, parakeratosis at hair follicle ostia
• Plan
  • Antifungal shampoo
  • Corticosteroid cream

Psoriasis / 乾癬

• Pathology
  • Chronic inflammatory dermatosis with autoimmune basis (environmental + genetic)
  • Result from T cell infiltration, cytokine secretion, keratinocyte proliferation
• Subjective
  • Multiple well-demarcated salmon-colored plaques with silver-white scale, often on elbow/knee/scalp
  • [Koebner phenomenon] New lesion induced by local trauma: Local inflammation becomes self-perpetuating
  • [Auspitz sign] Pinpoint bleeding when scales scraped off: Thinning of epidermis overlying dermal papillae
  • [Nail change] Pitting, onycholysis
  • [Psoriatic arthritis] Pain, deformity, associated with HLA-B27
• Objective
  • [Patho] Acanthosis, elongated rete ridges, hyperkeratosis, parakeratosis: Increased keratinocyte turnover rate
  • [Patho] Neutrophil aggregate in superficial epidermis (spongiform pustule) and stratum corneum (Munro microabscess): Local inflammation
• Assessment
  • [Type] Psoriasis vulgaris (most common): Erythematous plaques with white scale
  • [Type] Guttate psoriasis: Multiple small drop-shaped lesions
  • [Type] Pustular psoriasis: Localized or generalized lesions with pustules; including palmoplantar pustulosis
  • [Type] Palmoplantar pustulosis: Pustules on palms and soles, related to metal allergy and smoking; associated with sternocostoclavicular hyperostosis
  • [Type] Psoriatic erythroderma: Generalized erythroderma and scaling
• Plan
  • Topical therapy: Steroid, vitamin D
  • Light therapy: PUVA, UVB
  • Biological agents: Anti-TNFα, anti-IL17, anti-IL23

Lichen Planus / 扁平苔癬

• Pathology
  • Chronic inflammatory dermatosis
  • May be due to CD8+ T cells response elicited by altered antigen expressed in basal cell
• Subjective
  • Multiple pruritic purple papule/plaque with white lines on skin/mucosa
  • [Wickham striae] White lines in lace-like pattern: Hypergranulosis
  • [Koebner phenomenon] New lesion induced by local trauma: Local inflammation becomes self-perpetuating
• Objective
  • [Patho] Band-like lymphocytes infiltrate along dermoepidermal junction: Interface dermatitis
  • [Patho] Basal keratinocyte degeneration and squamatization, dermoepidermal interface sawtoothing: Destruction of basal cells
  • [Patho] Acanthosis, hypergranulosis, hyperkeratosis: Chronic changes
• Plan
  • Topical steroid

Blistering Disease / 水疱性疾患

Pemphigus / 天疱瘡

• Pathology
  • Blistering disease due to autoantibody against protein for adherence between keratinocytes (desmoglein)
• Subjective
  • Multiple flaccid bullae, rupture/erosion/erythema, in skin/mucosa: Dissolution of epidermis/epithelium
• Objective
  • [Patho] Acantholysis in deep epidermis (suprabasal blister), row of tombstones: In pemphigus vulgaris/vegetans, anti-Dsg3 (deep)
  • [Patho] Acantholysis in superficial epidermis (subcorneal blister): In pemphigus foliaceus/erythematosus, anti-Dsg1 (superficial)
  • [Patho] Net-like IgG deposit (all-layer for vulgaris, superficial for foliaceus): Autoantibody against desmoglein (component of desmosome)
  • [Serology] Anti-Dsg3 IgG (+) (vulgaris), anti-Dsg1 IgG (+) (foliaceus)
• Assessment
  • [Type] Pemphigus vulgaris (most common): Suprabasal blister, anti-Dsg3
  • [Type] Pemphigus vegetans: Vegetating plaques, anti-Dsg3
  • [Type] Pemphigus foliaceus (second common): Subcorneal blister, anti-Dsg1
  • [Type] Pemphigus erythematosus: Lupus-like erythema, anti-Dsg1
  • [Type] Paraneoplastic pemphigus: Often non-Hodgkin lymphoma
• Plan
  • Steroid, immunosuppressant

Bullous Pemphigoid / 水疱性類天疱瘡

• Pathology
  • Blistering disease due to autoantibody against protein for adherence of basal keratinocytes to basement membrane (BPAG2)
• Subjective
  • Multiple tense bullae, pruritic erythema, in skin/mucosa: Detachment of epidermis and dermis
• Objective
  • [Patho] Separation of basal keratinocytes and basement membrane (subepidermal blister), lymphocyte and eosinophil infiltrate: Due to anti-BPAG2
  • [Patho] Linear IgG deposit at dermoepidermal junction: Autoantibody against BPAG2 (component of hemidesmosome)
  • [Serology] Anti-BPAG2 IgG (+)
• Plan
  • Topical steroid
  • Tetracycline

Dermatitis Herpetiformis / 疱疹状皮膚炎

• Pathology
  • Blistering disease due to antibody cross-reacting with protein for anchoring of basement membrane to dermis (reticulin)
• Subjective
  • Pruritic grouped vesicles and erythema (urticaria)
• Objective
  • [Patho] Separation of basement membrane and superficial dermis (subepidermal blister), neutrophil infiltrate at tip of dermal papillae
  • [Patho] Granular IgA deposit at dermal papillae: Autoantibody against reticulin (anchoring fiber of basement membrane)
• Assessment
  • Often associated with celiac disease: IgA antibody cross-react to reticulin
• Plan
  • Topical steroid
  • Gluten-free diet: If associated with celiac disease

Epidermolysis Bullosa / 表皮水疱症

• Pathology
  • Blistering disease due to inherited defect in structural protein of skin
• Assessment
  • [Type] Simplex: Blister in basal cell layer, due to mutation of keratin 14/5
  • [Type] Junctional: Blister in lamina lucida, due to mutation of laminin
  • [Type] Dystrophic: Blister beneath lamina densa, due to mutation of COL7A1

Porphyria / ポルフィリン症

• Pathology
  • Congenital (or acquired) disturbances of porphyrin metabolism
• Subjective
  • Urticaria and vesicles, exacerbated by sun exposure
• Objective
  • [Patho] Subepidermal blister, abnormal vessel at superficial dermis
• Assessment
  • [Type] Congenital erythropoietic porphyria
  • [Type] Erythropoietic protoporphyria
  • [Type] Acute intermittent porphyria
  • [Type] Porphyria cutanea tarda

Skin Appendage Disease / 皮膚付属器疾患

Acne Vulgaris / 尋常性痤瘡

• Pathology
  • Inflammation of hair follicle and sebaceous gland
  • Contributed to keratin plug blocking sebum outflow, androgen inducing sebaceous gland hypertrophy, Propionibacterium acnes resulting in proinflammatory fatty acids
• Subjective
  • Erythematous papule/nodule/pustule, with/without central black keratin plug: Open/closed comedones
• Objective
  • [Patho] Open or closed comedones, immune cell infiltrate
• Plan
  • Antibiotics: For Propionibacterium acnes
  • Vitamin A derivative: Inhibit sebum production

Rosacea / 酒皶

• Pathology
  • Chronic inflammation around hair follicle, related to innate immune response
• Subjective
  • Persistent erythema/telangiectasia, papules/pustules, rhinophyma (nasal skin thickening)
• Objective
  • [Patho] Perifollicular lymphocyte infiltrate, dermal edema and telangiectasia

Panniculitis / 脂肪織炎

Erythema Nodosum / 結節性紅斑

• Pathology
  • Inflammation of subcutaneous fat septa, related to delayed hypersensitivity reaction
  • Causes include infection, drug, sarcoidosis, IBD, malignancy
• Subjective
  • Poorly-defined erythematous tender patch/nodule
• Objective
  • [Patho] Edema, fibrin exudation, and infiltration of subcutaneous fat septa

Erythema Induratum / 硬結性紅斑

• Pathology
  • Inflammation of subcutaneous fat lobule, related to vasculitis
  • Vasculitis of deep vessels supplying subcutaneous fat leads to fat necrosis
• Subjective
  • Erythematous slightly-tender nodule, often ulcerated: In lower extremity
• Objective
  • [Patho] Granulomatous inflammation and caseous necrosis of subcutaneous fat lobule

Infectious Disease / 感染症

Herpes Simplex / 単純疱疹

• Pathology
  • Viral infection caused by herpes simplex virus (HSV1/HSV2), primary or latent infection
  • Latent infection in trigeminal ganglion (HSV1) or sacral ganglion (HSV2), reactivated in immunocompromised state (stress)
• Subjective
  • [Labial] Painful vesicles on lips and perioral region
  • [Genital] Painful vesicles on external genitalia, symmetric ulceration
• Assessment
  • [Variant] Herpetic gingivostomatitis: Oral mucosa involvement in children
  • [Variant] Kaposi’s varicella form eruption: Widespread involvement in patient with weakened skin barrier (atopic dermatitis)
  • [Variant] Herpetic whitlow: Finger involvement in infant
• Objective
  • [Patho] Intraepithelial vesicles
  • [Cytology] Giant cell, inclusion body
• Plan
  • Anti-herpes drugs: Acyclovir and derivatives

Herpes Zoster / 帯状疱疹

• Pathology
  • Viral infection caused by varicella-zoster virus (VZV), latent infection (primary: chickenpox)
  • Latent infection in dorsal root ganglia, reactivated in immunocompromised state (aging, stress, malignancy, HIV, steroid)
• Subjective
  • Vesicles with erythema along dermatome (unilateral, band-like)
  • Neuropathic pain, may cause persistent neuralgia
• Assessment
  • [Variant] Ramsay Hunt syndrome: Facial palsy due to involvement of CN VII geniculate ganglion
• Plan
  • Anti-herpes drug: Acyclovir and derivatives
  • NSAID: For acute pain
  • Pregabalin: For post-herpetic neuralgia

Verruca / 疣贅

• Pathology
  • Viral infection caused by human papillomavirus (HPV), transmitted by direct contact
  • HPV 16/18 are carcinogenic due to E6 inhibiting p53
• Subjective
  • [Verruca vulgaris] Tan papules/nodules on various location
  • [Verruca plana] Slightly elevated papules on face/dorsal-hand
  • [Verruca plantaris] Ant-hill-like nodules on soles/palms
  • [Condyloma acuminata] Cauliflower-like mass on genitalia/anus
• Objective
  • [Patho] Papillomatous epidermal hyperplasia, cytoplasmic vacuolization (koilocytosis)
• Assessment
  • [Type] Verruca vulgaris: HPV 2/27/57
  • [Type] Verruca plana: HPV 3/10
  • [Type] Condyloma acuminatum: HPV 6/11
• Plan
  • [Verruca vulgaris] Topical salicylic acid, cryotherapy,
  • [Condyloma acuminatum] Topical imiquimod, cryotherapy

Molluscum Contagiosum / 伝染性軟属腫

• Pathology
  • Viral infection caused by a poxvirus, transmitted by direct contact
• Subjective
  • Multiple skin-colored umbilicated papules, curd-like material from central umbilication
• Objective
  • [Patho] Cup-like epidermal hyperplasia, molluscum body (large cytoplasmic inclusion) in stratum granulosum/corneum

Impetigo / 膿痂疹

• Pathology
  • Superficial bacterial infection caused by staphylococcus/streptococcus, highly contagious
  • Local invasion result in serous exudate (crust), exfoliative toxin cleave desmoglein 1 (blister)
• Subjective
  • Erythematous macule/patch with honey-colored crust (contagiosa) or blister/erosion (bullosa)
• Objective
  • [Patho] Neutrophil accumulation beneath stratum corneum
• Assessment
  • [Type] Impetigo contagiosa: Caused by β-hemolytic streptococcus (also S. aureus now)
  • [Type] Impetigo bullosa: Caused by Staphylococcus aureus
  • [Variant] Staphylococcal Scalded Skin Syndrome: Extensive shallow burn-like desquamation in infants due to release of staphylococcal exfoliative toxin into bloodstream

Tinea / 白癬

• Pathology
  • Superficial fungal infection caused by dermatophytes (mainly Trichophyton)
• Subjective
  • [Tinea capitis] Scalp, erythematous patch with hair loss
  • [Tinea corporis] Various location, expanding round erythematous patch
  • [Tinea cruris] Inguinal area, erythematous patch with scaly border
  • [Tinea pedis] Sole, diffuse erythema and scaling (interdigital, vesicular, hyperkeratotic)
  • [Tinea unguium] Nail, discoloration and thickening and deformity
  • [Tinea versicolor] Trunk, discolored macule or patch, caused by Malassezia furfur instead of dermatophyte
• Objective
  • [Patho] Red hyphae in stratum corneum under PAS stain
  • [KOH] Septate hyphae
• Plan
  • Topical azoles/allylamines

Scabies / 疥癬

• Pathology
  • Itchy skin rash caused by Sarcoptes scabiei parasitizing corneum layer, transmitted by direct or indirect contact
• Subjective
  • Extremely pruritic red papules
  • Track-like burrows (scabies burrow)
• Plan
  • Topical phenothrin, oral ivermectin

Orthopedic Surgery / 整形外科

Urology / 泌尿器科

Gynecology / 婦人科

Obstetrics / 産科

Pediatrics / 小児科

Dermatologic Disease / 皮膚疾患

• Subjective
  • Fish-like scale and dry skin, often since birth
• Objective
  • [Patho] Buildup of compacted stratum corneum
• Assessment
  • [Type] Ichthyosis vulgaris: Filaggrin gene mutation lead to impaired water retention
  • [Type] X-linked ichthyosis: Steroid sulfatase deficiency lead to excessive adherence of keratinocytes
  • [Type] Congenital ichthyosiform erythroderma: Erythema without blister
  • [Type] Epidermolytic ichthyosis: Erythema with blister
  • [Type] Lamellar ichthyosis
• Plan
  • Moisturizer: For dry skin
  • Salicylic acid: Soften and remove scales

Keratosis Follicularis / 毛包性角化症

• Pathology
  • Chronic keratotic papules due to ATP2A2 mutation
  • Also called Darier’s disease
• Subjective
  • Dark-brown keratotic papules in seborrheic/intertriginous part, onset in adolescence
  • With pruritus, exacerbated by sweat and sunlight
• Objective
  • [Patho] Hyperkeratosis, acantholysis
• Plan
  • Retinoid