Final answer:
Diffuse thinning of hair along the vertex, with sparing of the frontal hairline in a female patient may indicate polycystic ovary syndrome (PCOS).
Step-by-step explanation:
The patient in question is a female who presents with diffuse thinning of hair along the vertex, with sparing of the frontal hairline. Given the additional information provided, including irregular menstrual periods, excess facial hair, and acne, the most likely diagnosis is polycystic ovary syndrome (PCOS). PCOS is a hormonal disorder that affects the ovaries and can result in hair loss due to increased levels of androgens, or male hormones, which can disrupt the hair growth cycle. Effective treatment options for PCOS-related hair loss may include hormonal medications or topical treatments.