A patient presents with a pruritic, annular rash with fine scaling and central clearing, affecting the trunk and proximal extremities. The patient reports recent exposure to a new soap and laundry detergent. Which of the following conditions is most likely responsible for this presentation?

Correct Answer: B

Rationale: The presentation described is consistent with nummular eczema, also known as discoid eczema. Nummular eczema typically presents as circular or oval-shaped patches of eczematous rash with fine scaling and central clearing. It is often pruritic and can be triggered by exposure to irritants such as new soaps or laundry detergents. The distribution on the trunk and proximal extremities is also typical for nummular eczema. Tinea corporis (ringworm) would present with a more raised, scaly, and well-defined border with central clearing. Pityriasis rosea presents with a herald patch followed by smaller oval or round lesions in a "Christmas tree" distribution. Lichen planus would present with polygonal, purplish, flat-topped papules typically located on flexural surfaces and extremities.

Correct Answer: D

Rationale: The presentation of a small, painless, well-defined nodule on the lateral aspect of the neck, above the clavicle, along with the cytology showing clusters of polygonal cells with abundant granular cytoplasm is most indicative of a parathyroid adenoma. Parathyroid adenomas are benign tumors derived from the parathyroid gland that can produce excess parathyroid hormone (PTH), leading to hyperparathyroidism. The characteristic histology of parathyroid adenomas includes chief cells with abundant granular cytoplasm.

Correct Answer: A

Rationale: The sudden onset of severe vertigo, nausea, vomiting, and nystagmus in a patient with a recent upper respiratory tract infection is highly suggestive of vestibular neuritis. Vestibular neuritis is typically caused by inflammation of the vestibular nerve, often following a viral infection such as an upper respiratory tract infection. This condition presents with acute, severe, continuous vertigo without associated hearing loss. The presence of nystagmus, along with the absence of hearing loss, helps differentiate vestibular neuritis from Meniere's disease (which typically presents with episodic vertigo, hearing loss, and tinnitus) and acoustic neuroma (which presents with gradual onset of symptoms including unilateral hearing loss, tinnitus, and imbalance). Benign paroxysmal positional vertigo (BPPV) typically presents with brief episodes of vertigo triggered by specific head movements, rather than the continuous vertigo seen in this case.

Correct Answer: A

Rationale: The presentation described is characteristic of acute angle-closure glaucoma. This condition typically presents with sudden-onset severe eye pain, headache, nausea, and vomiting. On examination, the affected eye may appear red due to conjunctival injection, and there may be a steamy cornea due to corneal edema. The mid-dilated, non-reactive pupil is a key finding in angle-closure glaucoma, as the iris bombe (forward movement of the peripheral iris) blocks the drainage angle, leading to increased intraocular pressure. If left untreated, acute angle-closure glaucoma can result in irreversible vision loss. Immediate intervention is crucial to lower the intraocular pressure and prevent further damage to the optic nerve. Prompt referral to an ophthalmologist for definitive treatment is necessary in cases of suspected acute angle-closure glaucoma.

Correct Answer: C

Rationale: The described presentation of a yellowish-white spot on the cornea with a ring of inflammation, along with branching, filamentous opacities extending from the corneal lesion, is characteristic of fungal keratitis. Fungal keratitis typically presents with these specific features on clinical examination.