A 28-year-old patient comes to the office for evaluation of a rash. At first there was only one large patch, but then more lesions erupted suddenly on the back and torso; the lesions itch. On physical examination, you note that the pattern of eruption is like a Christmas tree and that there are a variety of erythematous papules and macules on the cleavage lines of the back. Based on this description, what is the most likely diagnosis?

Correct Answer: A

Rationale: The correct answer is A: Pityriasis rosea. The key features that point towards this diagnosis include the sudden eruption of lesions in a Christmas tree pattern on the back and torso, along with itching. Pityriasis rosea commonly presents with a single large patch followed by smaller lesions in a distinct pattern. Other choices can be ruled out based on the description provided. Tinea versicolor typically presents with hypo- or hyperpigmented patches, not the erythematous papules and macules described. Psoriasis usually presents with thick, silvery scales, not erythematous lesions in a Christmas tree pattern. Atopic eczema may present with erythematous papules, but the Christmas tree pattern and acute onset described are not typical.

Correct Answer: C

Rationale: The correct answer is C: Hordeolum. A hordeolum, also known as a stye, presents as a red raised tender area at the margin of the eyelid. In this case, the absence of tearing upon palpation of the lesion suggests it is localized to the eyelid itself. Dacryocystitis (choice A) involves the lacrimal sac and would present with tearing. A chalazion (choice B) is a painless nodule on the eyelid, unlike the tender lesion described here. Xanthelasma (choice D) is characterized by yellowish plaques on the eyelids, not a red raised tender area.

Correct Answer: B

Rationale: The correct term for the phenomenon described is "Consensual reaction" (Choice B). This occurs because the optic nerves from both eyes are connected, causing stimulation of one eye to result in a simultaneous response in the other eye due to the consensual pupillary reflex. The other choices are incorrect because: A: Direct reaction refers to the pupil directly exposed to light contracting. C: Near reaction refers to the pupillary response when focusing on a near object. D: Accommodation refers to the ability of the eye to adjust focus for near and far objects, not pupil constriction.

Correct Answer: C

Rationale: The correct answer is C: Efferent nerve damage on the right. When both pupils dilate but only the right pupil constricts briskly in response to light, it indicates a problem with the efferent pathway controlling the right eye's pupillary constriction. This suggests damage to the parasympathetic fibers of the oculomotor nerve (CN III) that innervate the pupillary sphincter muscle. Choices A and B (optic nerve damage) do not involve pupil constriction. Choice D (efferent nerve damage on the left) would not explain the brisk constriction in the right eye.

Correct Answer: D

Rationale: The correct answer is D because the 5th intercostal space is the recommended location for chest tube insertion to drain the pleural space effectively. This space is ideal as it allows for adequate drainage without causing injury to vital structures. A: The 2nd intercostal space is actually used for needle decompression in tension pneumothorax. B: T6 is the level at which the tip of the endotracheal tube should ideally lie to ensure proper placement and ventilation. C: The sternal angle corresponds to the 2nd rib, not the 4th rib, making this association incorrect. In summary, choice D is correct as it aligns with the standard practice for chest tube insertion, while choices A, B, and C are incorrect due to their association with different anatomic landmarks and procedures.