A 60-year-old woman with a history of breast cancer presents with a complaint of a new mass in her left breast. On examination, the mass is firm, non-tender, and fixed to the underlying tissue. What is the most likely diagnosis?

Correct Answer: C

Rationale: The most likely diagnosis is breast cancer recurrence (Choice C) due to the patient's history of breast cancer and the characteristics of the mass (firm, non-tender, fixed). Recurrence is common in breast cancer survivors. Fibrocystic changes (Choice A) typically present with lumpy or tender breasts and are not usually fixed. Breast abscess (Choice B) would present with more acute symptoms like redness, warmth, and fever. Fat necrosis (Choice D) may mimic a cancerous mass but is usually not fixed to underlying tissue. In this case, the history and characteristics of the mass strongly suggest breast cancer recurrence.

Correct Answer: B

Rationale: The correct answer is B: Cool, pale skin. Arterial insufficiency results in decreased blood flow to the extremities, leading to reduced skin temperature and pallor. Cool skin indicates diminished blood supply, while pale skin suggests vasoconstriction. Pitting edema (choice A) is a sign of venous insufficiency, not arterial. Brown discoloration (choice C) is characteristic of chronic venous insufficiency due to hemosiderin deposition. Warm, erythematous skin (choice D) is a sign of inflammation or infection, not arterial insufficiency.

Correct Answer: A

Rationale: The correct answer is A: Cerebellar dysfunction. When a patient sways significantly and loses balance while walking in a straight line, it suggests dysfunction of the cerebellum. The cerebellum is responsible for coordination, balance, and fine motor control. Impairment in the cerebellum can lead to ataxia, which is characterized by uncoordinated movements and difficulty maintaining balance. Vestibular impairment (B) primarily affects the inner ear's balance system, not coordination of movement. Motor weakness (C) typically presents as muscle weakness and affects strength, not balance. Peripheral neuropathy (D) involves damage to peripheral nerves, leading to sensory and motor deficits, but not specifically related to coordination and balance issues like cerebellar dysfunction.

Correct Answer: A

Rationale: The correct answer is A: Cerebellar dysfunction. When a patient staggers and loses balance while walking heel-to-toe, it indicates impairment in coordination and balance control, which are functions of the cerebellum. The cerebellum plays a crucial role in coordinating voluntary movements and maintaining balance. Vestibular dysfunction (B) primarily affects the inner ear's balance system, leading to vertigo and dizziness, not staggering gait. Sensory neuropathy (C) affects sensation, not coordination, and would not cause a specific gait abnormality. Motor weakness (D) would manifest as difficulty with strength and muscle control, not coordination issues seen in cerebellar dysfunction.

Correct Answer: B

Rationale: The correct answer is B: Frozen shoulder (adhesive capsulitis). Frozen shoulder is characterized by decreased range of motion in the shoulder joint with pain on movement. This is due to inflammation and thickening of the shoulder joint capsule, leading to adhesions that restrict movement. Other choices are incorrect because: A: Osteoarthritis primarily affects the joints, causing pain and stiffness but typically doesn't lead to severe restriction of range of motion like in frozen shoulder. C: Rheumatoid arthritis is a systemic autoimmune disorder that can affect multiple joints, causing inflammation and deformities, but it doesn't typically present with the characteristic pattern of restricted movement seen in frozen shoulder. D: Bursitis involves inflammation of the bursae (fluid-filled sacs) around joints, leading to pain and swelling, but it doesn't typically result in the severe restriction of movement and pain on movement seen in frozen shoulder.