INSTRUCTORS ONLY

Dermatopathology Lab

Objective: This dermatopathology laboratory session will illustrate the histopathologic findings of several common dermatologic conditions. Basic clinical material from the lecture series will be reinforced.

CASE 1

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History: A 12-year-old boy complained of a slowly growing papule with a thickened surface on his finger. The lesion was biopsied.

Histologic features: There is hyperkeratosis, papillomatosus, and acanthosis. Within the granular cell layer, diagnostic koilocytes containing "raisin-like" nuclei are seen. Intracytoplasmic viral inclusions may also occasionally be seen.

Diagnosis: Viral verruca (wart)

1. What is the cause of viral verrucas?

2. How does a person become infected with warts?

3. Can HPV infection be associated with malignancy?

CASE 2

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History: A 30-year-old woman presented with a symmetric, uniformly pigmented, dome-shaped papule on her face. She requests its removal.

Histologic features: There is a dome-shaped, symmetric papule with multiple nests of bland nevus cells at the dermo-epidermal junction and in the dermis. Nevus cells are slightly larger in the superficial portion of the lesion and become smaller or "mature" with descent into the dermis. There is no cytologic atypia.

Diagnosis: Compound nevus

1. What is the cell of origin of a compound nevus?

2. Can common acquired nevi serve as melanoma precursors?

3. Name two other types of melanocytic nevi that are at greater risk for the development of melanoma than common acquired benign nevi.

CASE 3

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History: A 24-year-old medical student, who used to work summers as a lifeguard, complained of a changing mole on her leg. It had begun to itch and recently darkened in color. The lesion was biopsied.

Histologic features: There are cytologically atypical melanocytes at the dermo-epidermal junction and in the dermis. Pagetoid involvement of the epidermis may be seen. Nuclei are large with occasionally prominent nucleoli. Rare mitotic figures are present. The lesion is asymmetric and poorly circumscribed.

Diagnosis: Melanoma

1. What is the single most important finding the dermatopathologist should include in his/her report of melanoma?

2. List the risk factors for the development of melanoma.

3. What are the ABCD's of melanoma?

CASE 4

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History: A 65-year-old man complained of a slowly growing lesion on his nose. On exam, an ulcerated pearly nodule with surface telangiectasia was noted. The lesion was biopsied.

Histologic features: There are multiple basaloid tumor islands demonstrating peripheral palisading and stromal retraction artifact. Connection to the epidermis is often identified.

Diagnosis: Basal cell carcinoma

1. What is the most common cancer in humans?

2. What environmental factor predisposes to the development of basal cell carcinoma?

3. In what location does basal cell carcinoma most frequently develop?

4. What is the usual biologic behavior of basal cell carcinoma? What is its metastatic potential?

CASE 5

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History: A 45-year-old woman complained of a scaly rash present for many years. On exam were multiple, well demarcated erythematous papulosquamous plaques on the elbows, arms and knees. Erythema and white scale were also present on her scalp. A skin biopsy was taken.

Histologic features: There is near confluent parakeratosis, hypogranulosis, and regular psoriasiform hyperplasia of the epidermis with slight clubbing of the rete pegs. Neutrophilic fragments can be identified in the stratum corneum forming Munro's microabscesses and in the upper epidermis forming spongiform pustules of Kogoj. Dilated and tortuous blood vessels are seen in the dermal papillary tips.

Diagnosis: Psoriasis

1. List several morphologic variants of psoriasis.

2. What is guttate psoriasis typically found in association with?

CASE 6

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History: A 35-year-old man was clearing a path in the woods. When he returned home, he noticed an intensely pruritic linear vesicular eruption on his extensor forearms. A skin biopsy was taken.

Histologic features: There is pronounced spongiosis (intercellular edema) within the epidermis resulting in intraepidermal vesicles. Exocytosis of lymphocytes (lymphocytic spongiosis) may be seen in the epidermis. There is a superficial perivascular lymphocytic infiltrate.

Diagnosis: Acute spongiotic dermatitis consistent with acute allergic contact dermatitis ("contact hypersensitivity" to poison ivy)

1. Contact dermatitis to poison ivy is an example of what type of allergic hypersensitivity reaction?

2. Does allergic contact dermatitis occur with someone's first exposure to the antigen?

The answers to the path lab questions will be posted approximately 48-72 hours after the lab sessions. These are abbreviated answers, not a full discussion of the topics. You can find them in the M2 CTools site resources. In the folder for each sequence the will be a folder called 'Path Lab Resources'