Pathophysiology
Why do melanocytes express the glial marker S-100?
Because melanocytes original arose from neural crest tissue
Identify this sample
Squamous Cell Carcinoma
A patient presents to the dermatologist with a suspicious mole which would warrant biopsy. The patient is on DAPT for atrial fibrillation, which is the best diagnostic test to rule out melanoma.
Still do the biopsy :)
What is the preferred treatment modality for high risk BCC
Mohs surgery with margins
Do sensory neurons leave the spinal cord dorsally or ventrally?
Dorsally
A mutation in this tumor suppressor is observed in Melanoma oncogenesis
Double Jeopardy: What is the function of said gene?
CDKN2A
Encodes for p16 and p14 which inhibit CDK4/CDK6 and stabilize p53 respectively.
Identify this sample.
Basal Cell Carcinoma
This metric holds the most prognostic weight when staging Melanoma
Breslow Thickness
What mutated protein is the target of the anti-melanoma drug Vemurafenib
V600E BRAF
Free nerve endings in the skin are composed of alpha-delta and C fibers which are thinly myelinated and unmyelinated respectively. Which fiber would be better suited for detecting sharp pain.
Alpha-delta
BCC arises from unopposed hedgehog pathway activation. Which gene is lost allowing for oncogenic progression
PTCH1
Identify this sample
Nodular Melanoma
This marker commonly expressed on schwann cells, is upregulated in advanced disease compared to local lesions
S-100
What are two topical chemotherapies that can be used in the treatment of BCC
Topical imiquimod 5% and or topical fluorouracil (5-FU)
Merkel cells transduce light touch into neuronal signals. What type of nerve fibers carry these signals.
Alpha-beta
Most benign nevi contain a BRAF mutation. Why is it then that these moles stay benign and do not transform into melanoma?
Because CDKN2A provides cell cycle inhibition after initial clonal proliferation of the melanocyte.
Identify this sample
Double Jeopardy: Identify all 5 layers of the skin based on the following histology.
Normal skin :)
A 53 year old patient presents with a lesion on his lower lip later determined to be malignant. What is another risk factor besides UV exposure that predisposes an individual to this type of malignancy?
Immunocompromised, non healing wounds, arsenic exposure.
In our patients' case radiation therapy was added on after surgical respect with clear margins. Justify why this was performed.
Merkel cell carcinoma has a high rate of recurrence tied to microscopic satellite lesions within the tumor bed/margins.
Identify the following sensory organ.
Meissner Corpuscle
Within NBME study material basal cell carcinoma is commonly described as a cancer of the upper lip. Why does BCC “favor” the upper lip.
BCC arises from hair follicle stem cells which the upper lip possesses.
Identify this sample
Actinic Keratosis
What IHC marker combination indicate Merkel Cell Carcinoma
CD20+/TTF-/CK7-
The current standard of care in recurrent disease for our patients malignancy is sold under the generic name Pembrolizumab. Explain how this biologic works to drive an antitumor response.
By binding to PD-1 on T cells, CD8 cytotoxic T cells are “activated” and allowed to target malignant cells by preventing PD-1 PD-L1 binding.
Match the following sensory organ with its function: Meissner corpuscles, Pacinian corpuscles, Merkel discs, Ruffni corpuscles
Meissner - fine light touch, low frequency vibrations
Pacinian - high frequency vibrations, pressure
Merkle - pressure, deep touch,
Ruffni - stretch, joint angle change