WBR0779

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology
Sub Category	SubCategory::Dermatology
Prompt	[[Prompt::A 21-year-old woman presents to the dermatology clinic for a lesion on her right arm. The patient explains that the lesion has been expanding slowly. She describes it as scaly but neither itchy nor painful. She notices that the lesion bleeds when she scratches it or tries to lift off the overlying scale. The patient reports she has never had any similar lesions, but her grandma used to complain of similar scales on her arms and legs. On physical exam, you notice a well demarcated erythematous plaque covered by a fine, and loosely adherent, silvery-white scale. If you were to biopsy the lesion, what would you most likely find on microscopic examination?]]
Answer A	AnswerA::Civatte bodies
Answer A Explanation	AnswerAExp::Civatte bodies are typically seen in lichen planus.
Answer B	AnswerB::Munro microabscesses
Answer B Explanation	AnswerBExp::Munro microabscesses are neutrophilic accumulations in the stratum corneum characteristic of psoriasis.
Answer C	AnswerC::Psammoma bodies
Answer C Explanation	AnswerCExp::Psammoma bodies are calcified whorls seen in meningioma, serous cystadenocarcinoma of the ovary, papillary thyroid carcinoma, and mesothelioma.
Answer D	AnswerD::Paget’s cells
Answer D Explanation	AnswerDExp::Paget cells are typically found in Paget's disease.
Answer E	AnswerE::Horn cysts
Answer E Explanation	AnswerEExp::Horn cysts are characteristic of seborrheic keratosis.
Right Answer	RightAnswer::B
Explanation	[[Explanation::Psoriasis is an inflammatory skin disorder characterized by silvery white scales usually seen on the scalp, knees, and elbows. It is a T-lymphocyte associated auto-immune disease. Prevalence is estimated at 2% of the general population. Nail involvement and psoriatic arthritis can be seen in up to 25% of patients. Classically the plaques exhibit punctate bleeding when the scale is peeled off. This is known as the Auspitz sign. Features on pathological examination of a psoriatic lesion include keratinocyte hyperproliferation and hyperkeratosis, as well as leukocytic infiltration and angiogenesis. The stratum spinosum is usually thickened while the stratum granulosum becomes thinner. Neutrophils migrate to the epidermis then form Munro microabscesses which are characteristic of psoriasis. Educational Objective: Psoriasis is an inflammatory skin disorder characterized on pathology by hyperkeratosis, angiogenesis, thickening of the stratum spinosum and munro microabscesses. References: Schön MP, Boehncke WH. Psoriasis. N Engl J Med. 2005;352(18):1899-912.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Psoriasis, WBRKeyword::Munro microabscesses, WBRKeyword::Hyperkeratosis, WBRKeyword::Auspitz sign, WBRKeyword::Scale
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::