On visualization of the penis he is circumcised and there are no lesions and no discharge from the meatus. His scrotal skin is tense and red. Palpation of the left testicle causes severe pain and the patient begins to cry. His prostate examination is unremarkable. His cremasteric reflex is absent on the left but is normal on the right. By catheter you get a urine sample and the analysis is unremarkable. You send the boy with his mother to the emergency room for further workup. What is the most likely diagnosis for this young man's symptoms?

Correct Answer: C

Rationale: The presentation of severe testicular pain with a red, tense scrotum, and absent cremasteric reflex on one side is highly concerning for testicular torsion. Testicular torsion is a urologic emergency that occurs when the spermatic cord twists, leading to compromised blood flow to the testicle. The affected testicle can become ischemic and necrotic within hours, necessitating prompt diagnosis and intervention to avoid permanent damage or loss of the testicle.

Correct Answer: A

Rationale: When crackles, wheezes, or rhonchi clear with a cough, it is suggestive of bronchitis. Bronchitis is inflammation of the bronchial tubes, often due to a viral infection, leading to the production of excess mucus. The characteristic sounds such as crackles, wheezes, or rhonchi can be heard on auscultation due to the presence of mucus in the airways. The act of coughing helps to clear the mucus from the airways, resulting in the temporary resolution of these abnormal sounds. In contrast, asthma, cystic fibrosis, and heart failure are not typically associated with crackles, wheezes, or rhonchi that clear with a cough.

Correct Answer: B

Rationale: In the given scenario, being a 35-year-old archaeologist with fair skin, a family history of melanoma, and many freckles scattered across her skin are all risk factors for melanoma. Age (choice A) is a relevant risk factor as melanoma incidence increases with age. Actinic lentigines (choice C), also known as sunspots, are precancerous skin lesions that can increase the risk of developing melanoma. Heavy sun exposure (choice D) is a significant risk factor as cumulative sun exposure over time can contribute to the development of melanoma.

Correct Answer: D

Rationale: The presentation is highly suggestive of appendicitis, especially given the migration of pain from the periumbilical region to the right lower quadrant (just medial and inferior to the iliac crest). The worsening of pain with motion, along with associated symptoms such as nausea, vomiting, anorexia, and fever, are typical features of appendicitis. The classic presentation of appendicitis is pain starting around the umbilicus (due to visceral innervation) and then shifting to the right lower quadrant (due to irritation of the parietal peritoneum). Surgical intervention is usually required promptly to prevent complications like perforation, which can lead to peritonitis and sepsis.

Correct Answer: B

Rationale: The presentation of multiple burning erosions on the shaft of the penis along with tender inguinal adenopathy is indicative of genital herpes caused by the herpes simplex virus (HSV). Primary herpes simplex infection typically presents with painful ulcers and lymphadenopathy. The ulcers are often shallow with well-defined borders and can be associated with systemic symptoms such as fever and malaise. In contrast, primary syphilis is characterized by a painless chancre at the site of infection, usually on the genitals. Chancroid can also present with painful ulcers, but it is less common in developed countries. Gonorrhea typically presents with urethral discharge, dysuria, or other symptoms of urethritis, rather than erosions on the penis shaft.

Correct Answer: C

Rationale: The symptoms described, such as sneezing, itchy watery eyes, clear nasal discharge, ear pain, and nonproductive cough, are classic signs of allergic rhinitis, commonly known as seasonal allergies. Allergic rhinitis is an inflammatory response triggered by allergens in the environment such as pollen, dust mites, or pet dander. The immune system overreacts to these allergens, releasing histamine and other chemicals that cause the symptoms experienced by the patient. In this case, the most likely pathologic process underlying the symptoms is an allergic response rather than infection, inflammation, or vascular issues.

Correct Answer: D

Rationale: The given symptoms of distant air sounds, late inspiratory crackles in both lower lobes, distant S1 and S2 heart sounds, and an S3 heart sound heard over the apex are all characteristic findings of left-sided heart failure. Distant air sounds and late inspiratory crackles indicate pulmonary congestion due to fluid accumulation in the lungs as a result of left-sided heart failure. The distant heart sounds and presence of an S3 are signs of left ventricular dysfunction. In contrast, pneumonia would typically present with more localized abnormal breath sounds and other symptoms such as fever and productive cough. Chronic obstructive pulmonary disease (COPD) would manifest with prolonged expiratory phase and wheezing, not late inspiratory crackles. Pleural pain is typically associated with sharp chest pain exacerbated by breathing movements, and it does not explain the constellation of symptoms described in this case. Therefore, the most likely diagnosis based on the provided symptoms

Correct Answer: D

Rationale: A rectal polyp is a growth that originates from the inner lining of the rectum and protrudes into the rectal canal. It may present as a soft, smooth, nontender mass on digital rectal examination. Rectal polyps are usually benign, but some may have the potential to become cancerous if left untreated. Therefore, it is important to evaluate and remove polyps to prevent complications. In this case, the description of a pedunculated mass on the posterior wall of the rectum is most suggestive of a rectal polyp.

Correct Answer: D

Rationale: The most likely cause of the 19-year-old college sophomore's joint pain is Lyme disease. The presentation of a red spot shaped like a target (erythema migrans) that spreads, along with joint pain, is classic for Lyme disease. Additionally, the history of camping in an area known to have ticks and the history of using insect repellent support the likelihood of a tick-borne illness like Lyme disease.