Derm In Review - Dermatopathology

Question 1

What do eccrine glands stain positive for?

Answer 1

S-100 and CEA

Question 2

What is giemsa stain used for?

Answer 2

Stains mast cell granules (heparin in the granules) and Leishmaniasis

Question 3

The predominant location of the cleft in cicatricial pemphigoid is what?

Answer 3

BMZ

Question 4

The histologic finding of “shoulder parakaratosis”, parakeratosis with prediliection for the follicular ostia, is characteristic of pityriasis rubra pilaris as well as what other skin condition?

Answer 4

Seborrheic dermatitis

Question 5

Where is the inflammation in each of the following?

• Alopecia areata
• Discoid lupus
• Lichen planopilaris

Answer 5

• Alopecia areata → hair bulb
• Discoid lupus → isthmus
• Lichen planopilaris → infundibulum

Question 6

Which marker helps to differentiate extranodal NK-T cell lymphoma from cutaneous gamma delta lymphoma?

Answer 6

EBV status

Both cutaneous gamma delta lymphoma and extranodal NK-T cell lymphoma are CD56+. However, only extranodal NK-T cell lymphoma is EBV + while cutaneous gamma delta lymphoma is EBV negative. Both these lymphomas have a 5-year survival rate that approaches 0%.

Question 7

This tumor is vimentin+ and cytokeratin+.

Answer 7

Epithelioid sarcoma

Characteristic immunohistochemistry of epithelioid sarcoma is vimentin and cytokeratin positivity.

Question 8

The pigment deposits in ochronosis are accentuated with what two stains?

Answer 8

Cresyl violet and methylene blue stains pigment deposits black

Question 9

A patient presents with recurrent crops of papules that ulcerate and then spontaneously heal. What immunohistochemical stain would be helpful in making the diagnosis?

Answer 9

CD30

Lymphomatoid papulosis

Question 10

The PDGF gene has been shown to be translocated into the collagen I gene in what skin lesion?

Answer 10

DFSP

Question 11

Guarnieri bodies can be found associated with which of the following viral infections?

Answer 11

Variola (smallpox)

Guarnieri bodies are eosinophilic intracytoplasmic inclusions associated with variola infection (smallpox), however they can also be seen in infections with other pox viridae including vaccinia, cowpox, and parapox. These inclusions represent aggregates of viral particles.

Question 12

The predominant location of the cleft in acropustulosis of infancy is where?

Answer 12

Subcorneal/granular layer

Question 13

Mantle cell lymphoma is characteristically positive for what?

Answer 13

Bcl-1 (cyclin D1)

Question 14

Methyl-green pyronin stains RNA what color? What about DNA?

Answer 14

RNA is stained pink.

DNA is stained green.

Question 15

You diagnose a patient with multiple epidermal tumors that on histopathology shows a fibrous pink orb with epithelial strands coming through the follicular center. The patient most likely has a mutation in which gene?

Answer 15

FLCN

This describes a fibrofolliculoma, a tumor seen in Birt-Hogg-Dubé syndrome. This is an autosomally dominant syndrome due to a mutation in FLCN - folliculin (Choice 3), a tumor suppressor gene. Patients show these skin lesions and have an increased risk for renal cell carcinoma, spontaneous pneumothoraces, pulmonary cysts, and medullary carcinoma of the thyroid.

Question 16

On histology this disease has mucin deposition within the external root sheath and sebaceous gland. The mucin distends into the intracellular spaces within follicular epithelium forming cystic cavities. The following stains will be positive EXCEPT for which one of the following:

• CD4
• CD9
• CD7
• CD8
• CD3

Answer 16

CD9

Follicular mucinosis

Question 17

Mulberry cells contain increased number of what cellular organelle?

Answer 17

Mitochondria

Mulberry cells are seen in hibernoma.

Question 18

Metastatic renal cell carcinoma stains positive for what? (3)

Answer 18

Epithelioid membrane antigen, carcinoembryonic antigen, CD-10, renal cell carcinoma marker are markers used to identify skin metastases of renal cell carcinoma.

Question 19

What two stains does cellular neurothekeoma stains with?

Answer 19

S-100a6 and PGP-9.5

Question 20

The differential for parasitized macrophages can be remembered using the mnemonic His GIRL Penelope:

Answer 20

His-Histoplasmosis
GI-Granuloma inguinale (aka Donovanosis)
R- Rhinoscleroma (not to be confused with Rhinosporidiosis)
L- Leishmaniasis
Penelope- Penicilliosis

Question 21

Which type of PRP is most common in children?

Answer 21

Type IV

In PRP, type 4 is circumscribed juvenile version, which is the most common form in kids.

Type 1 is classic adult. Type 2 is atyical, chronic adult. Type 3 is classic juvenile, type 5 is atypical juvenile. A sixth form associated with HIV has been described as well.

Question 22

What is the treatment of choice for a MCC without LAD?

Answer 22

WLE with SNLB

The preferred treatment for a tumor on the trunk without clinically apparent lymphadenopathy is wide local excision (1-3 cm margins) and sentinel lymph node biopsy. If the lymph node biopsy is positive, then the patient will likely require radiation therapy. For lesions >2cm, some clinicians will not perform a sentinel lymph node biopsy since radiation therapy is indicated regardless, given the high risk of lymph node metastasis.

Question 23

Grenz zone differential

Answer 23

Lepromatous leprosy, cutaneous B cell lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, acute myelomonocytic leukemia, leiomyosarcoma, and Botryoid rhabdomyosarcoma.