A 23-year-old woman, gravida 2 para 1, at 39 weeks gestation comes to the labor and delivery unit with regular painful contractions.  The patient’s first pregnancy was uncomplicated and resulted in a full-term, spontaneous vaginal delivery 3 years ago, and her current pregnancy has been uncomplicated.  She takes a prenatal vitamin daily and has no chronic medical conditions.  In response to rising estrogen levels, the patient’s myometrial cells increase the expression of genes that encode the oxytocin receptor and connexin 43.  These molecular changes most likely result in increased formation of which of the following?

A 68-year-old man with a history of Parkinson disease is hospitalized for pneumonia and sepsis.  The patient is treated with intravenous (IV) fluids and antibiotics.  He is also started on an infusion of IV dopamine for hemodynamic support.  Although the manifestations of Parkinson disease are attributed to dopaminergic neuron degeneration in the substantia nigra, IV dopamine does not improve this patient’s Parkinson symptoms.  Which of the following cell structures accounts for this lack of responsiveness?

A 20-year-old woman comes to the office due to blisters around her mouth associated with a mild burning sensation.  She reports that she has been having frequent recurrence of these lesions, which resolve spontaneously within a few days.  She has no medical problems and does not take any medications.  Physical examination findings are shown in the image below.

It is determined that the causative organism of this patient’s condition remains in a latent state in the neuronal cell bodies of sensory ganglia.  Upon reactivation, the virus is transported through the nerve axon to the skin.  Which of the following proteins is most likely involved in the transport process leading to disease recurrence?

A 45-year-old man is brought to the emergency department due to new-onset seizure.  His family witnessed an episode of blank staring followed by a generalized tonic-clonic convulsion with tongue biting and urinary incontinence.  The patient has a past medical history of seasonal asthma and takes no prescription medications.  He does not use alcohol or illicit drugs.  Vital signs and neurologic examination are normal.  Noncontrast head CT and brain MRI are consistent with a diagnosis of cavernous hemangioma.  This patient is at greatest risk of developing which of the following complications?

A 30-year-old man with a history of epilepsy comes to the office for follow-up.  He has a history of recurrent seizures that start as jerky, rhythmic movements of his left leg and gradually spread to involve the entire left side of his body.  The patient frequently loses consciousness and has been witnessed to have a generalized tonic-clonic seizure.  Neuroimaging has revealed a focal lesion in the right motor area.  He has been treated with several antiepilepsy drugs, but his seizures have remained poorly controlled.  Surgery is performed to remove the lesion, and the excised brain tissue shows a 1.5-cm mass composed of engorged purplish clusters.  Microscopy shows numerous dilated capillaries with an endothelial lining separated by a thin layer of fibrous connective tissue.  Which of the following is the most likely diagnosis?

A 45-year-old woman is brought to the emergency department after a generalized tonic-clonic seizure.  She reports no prior history of seizures, but she has noticed right arm weakness over the last week.  Her family history is significant for her mother’s death from skin cancer.  Physical examination shows a skin lesion measuring 13 mm on her back, as shown in the image below.

This lesion most likely originated from which of the following embryologic derivatives?

A 65-year-old man comes to the office due to fatigue, decreased appetite, and weight loss.  He has lost 5.4 kg (12 lb) over the last 3 months and eats only small portions of food because he feels full soon after he begins eating.  The patient smokes a pack of cigarettes per day and drinks alcohol socially.  Blood pressure is 152/90 mm Hg and pulse is 90/min.  Physical examination shows a firm, 3-cm lymph node above the left clavicle.  Numerous skin lesions are seen on the patient’s trunk, as shown below; the lesions were not present during his last physical examination 1 year ago.

Which of the following is the most likely diagnosis of this patient’s skin lesions?

A 22-year-old woman comes to the office due to several years of persistent facial blemishing that has failed to respond to over-the-counter treatment.  The patient has no other medical conditions.  She does not use tobacco, alcohol, or illicit drugs.  Skin examination findings are shown in the image below:

Which of the following most likely contributed to the pathogenesis of this patient’s skin condition?

An 8-year-old boy is brought to the office due to a lower extremity skin rash for the past 3 days.  The rash began as tender papules that quickly progressed to form vesicles and flaccid bullae that rupture easily.  The patient has no mucosal lesions or other rashes and has never had similar symptoms before.  He is up to date with recommended vaccinations and takes no medications.  Skin examination findings are shown below.

Which of the following is the most likely cause of this patient’s skin findings?

A 28-year-old man comes to the office to discuss hair loss.  He has hair loss primarily around the temples, which began insidiously 3 years ago.  The patient is concerned because several of his family members became almost completely bald by their late 30s.  He otherwise feels healthy and has normal muscle strength, libido, and erectile function.  The patient is married, has 2 children, and works as a charter airplane pilot.  Physical examination shows moderate thinning of hair at the anterior scalp, temporal region, and vertex.  An oral medication is prescribed to treat the hair loss.  After the initiation of therapy, which of the following changes would most likely occur in this patient?

A 28-year-old, previously healthy woman comes to the office for evaluation of a raised, pigmented skin lesion on her leg.  The patient has had no itching or pain and cannot remember how long she has had the lesion.  She has used tanning machines a few times but denies excessive sun exposure.  The patient is particularly concerned about the risk for malignancy because her father was recently diagnosed with skin cancer.  The skin lesion is shown in the image below:

Biopsy of the lesion reveals nests of round, uniform cells at the basal portion of the epidermis that extend into the underlying dermis.  The cells contain inconspicuous nucleoli and show no mitotic activity.  Which of the following is the most likely diagnosis?

A 52-year-old woman comes to the office due to a 2-month history of oral lesions that cause pain with chewing and swallowing food.  The patient did not seek treatment because she thought the lesions would go away on their own, but they have persisted.  On examination, there are erosions of the buccal and gingival mucosa, as shown in the image below.  There are several flaccid bullae with erosions scattered over her trunk.  The blisters spread laterally with pressure, and traction on seemingly uninvolved skin produces blistering.  Autoantibodies directed against which of the following structures are most likely responsible for this process?

A 6mm punch biopsy of normal appearing epidermis reveals stellar cells that contain intracytoplasmic granules having the shape of a tennis racquet.  These cells demonstrate some myeloid surface markers and can interact closely with T lymphocytes.  The cells described above are best referred to as which of the following?

A 27-year-old man comes to the office for evaluation of a rash on both knees.  The patient first noticed the rash 2 months ago.  He has no other medical conditions and takes no medications.  The patient smokes a half pack of cigarettes daily.  Vital signs are normal.  His knee is shown in the image below:

Removal of the scale results in small bleeding points.  As part of the treatment regimen, a topical vitamin D analog is prescribed.  This medication is most likely to improve this patient’s condition via which of the following mechanisms?

A 64-year-old man comes to the office for evaluation of several lesions on his forehead.  The patient has been a gardener for much of his life.  The photograph below shows findings from the physical examination.

On palpation, the lesions have a rough grainy texture.  Biopsy reveals atypical keratinocytes with hyperkeratosis and parakeratosis.  This patient’s lesions put him at greatest risk for developing which of the following conditions?

A 27-year-old woman comes to the emergency department with a scalp laceration after a fall.  She reports a tendency to develop big scars even with small injuries.  Physical examination reveals an old, healed laceration as shown in the image below.

Histochemical analysis of her tissue reveals fibroblasts that overexpress a cytokine essential for normal wound healing.  Which of the following substances is most likely involved?

A 56-year-old woman comes to the office due to a pigmented lesion on her back.  She first noted the lesion a year ago and says it has enlarged.  Past medical history is unremarkable.  The patient has worked as a forest service ranger for the last 30 years and has spent much of her time outdoors.  On examination, there is a large irregular pigmented lesion on the upper back, as shown in the exhibit, as well as scattered patches of erythema and telangiectasias.  Excisional biopsy of the lesion shows malignant melanoma.  Which of the following is associated with the highest risk of metastasis for this patient’s lesion?

A 58-year-old man comes to the physician for evaluation of skin lesions on his forehead.  He says that he first noticed the lesions when he was rubbing his forehead because of their roughness.  His medical problems include hypertension that is well controlled with chlorthalidone.  He has worked as a construction foreman for 32 years.  Physical examination shows the findings seen in the image below.

Which of the following is the most likely diagnosis?

A 36-year-old man comes to the office due to a 2-month history of a pruritic rash over the elbows and knees.  The patient has been using skin emollients, but the lesions have not improved.  He also has a prolonged history of episodic abdominal discomfort, flatulence, and voluminous greasy stools.  Cardiopulmonary examination is normal.  The abdomen is soft and nontender.  Skin examination shows a papulovesicular skin rash in groups with erosion and excoriations.  Which of the following is most likely to be seen in this patient?

A 28-year-old man comes to the office with bilateral skin lesions over the posterior surface of the elbows.  The lesions are itchy at times; topical moisturizers have reduced the itching, but the lesions have remained.  The patient has no chronic medical problems and takes no medications.  Biopsy of the lesions demonstrates hyperkeratosis, parakeratosis, dilated capillaries in the dermal papillae, and foci of neutrophils in the superficial epidermis.  Which of the following is the most likely diagnosis?

A 34-year-old man comes to the office due to a persistent skin rash.  He has a 6-month history of a scaly rash involving the upper and lower extremities that is associated with mild pruritus.  The patient has attempted treatment with topical antihistamines and emollients without relief.  Medical history is notable for childhood asthma and orolabial herpes simplex virus infection.  He does not use tobacco or alcohol and works as a sales associate for a home improvement store.  On examination, the patient has skin lesions as shown in the image below.

This patient’s disorder is most likely associated with which of the following extradermal complications?

An 18-year-old man comes to the office due to acne.  The patient has had mild facial acne for the past 3 years that has responded well to topical agents.  Since he started college 2 months ago, the acne has worsened and has spread to his torso and neck.  Despite use of the topical agents, it has continued to worsen.  The patient plays on the university’s baseball team, which requires him to practice outdoors for several hours 3 days a week.  He also swims in an indoor pool several hours a week.  Since starting college, the patient has adopted a dairy-free, low-glycemic-index diet.  Physical examination shows severe, nodulocystic acne on the face, neck, chest, and back.  Which of the following most likely caused this patient’s worsening acne?

A 34-year-old female presents with a small bluish lesion under the nail of her right index finger.  The lesion is extremely tender to touch.  If the lesion is a tumor, its cells of origin are most likely to have which of the following functions:

A 46-year-old man comes to the office with the skin lesions shown in the photograph below.  The patient first noticed the lesions a week ago after he returned from a trip to Hawaii.  He has not had any other significant rashes or skin lesions but does have a history of autoimmune thyroiditis.

Which of the following would most likely be seen on histopathologic examination of this patient’s lesions?

A 32-year-old woman is brought to the emergency department due to “bruising.”  She has a chronic mental disability and lives in a group home.  Care staff members accompanying the patient report that she fell 3 days ago but has not mentioned any pain.  No signs of injury were noted until a large area of discoloration was seen at the upper arm during bathing.  Past medical history is unremarkable, and the patient takes no medications.  Vital signs are normal.  Skin examination findings are shown in the image below.  There is no associated warmth, and the patient shows no signs of discomfort during palpation of the affected area.

Which of the following terms best describes this abnormality?

A 53-year-old woman comes to the clinic due to a rash.  For the past 3 weeks, she has had a pruritic rash of worsening severity involving the posterior thighs.  The patient recently began an exercise program to lose weight and has been applying a topical analgesic cream to her thighs and buttocks after her workouts to relieve muscle aches.  Medical history is unremarkable, and she does not use tobacco, alcohol, or recreational drugs.  On physical examination, there is an erythematous rash with blisters, erosions, and weeping drainage involving the posterior thighs bilaterally, which is shown in the image below:

Which of the following is the most likely finding on skin biopsy?

A 24-year-old woman comes to the office due to worsening acne.  Over the past 3 months, the patient has had frequent breakouts on the shoulders and upper back.  She had acne on her face during puberty, which cleared spontaneously after several years, but has never before had symptoms on her trunk.  The patient has no other medical conditions, and her only medication is a combination oral contraceptive.  She has been training for a half-marathon for the past 4 months and has lost 6.8 kg (15 lb) during this period.  She does not use tobacco, alcohol, or illicit drugs, and she relocated from California to Wisconsin for work a year ago.  Vital signs are within normal limits.  Physical examination shows acneiform eruptions on the shoulders and mid-back.  Which of the following is most likely contributing to worsening of this patient’s acne?

An 18-year-old man has chronic atopic dermatitis.  He has been applying a corticosteroid cream daily to the flexural areas of his skin for several years, and the treated areas have been free of pruritus, papules, vesicles, and scales during that time.  Medical history is notable for asthma and allergic rhinitis.  Punch biopsy of the treated skin would most likely show which of the following findings?

A 64-year-old man comes to the office due to blisters on his trunk and groin.  Itching has occurred for the past several weeks, and blisters developed a week ago.  He has a history of hypertension and osteoarthritis.  The patient received the zoster vaccine at age 60.  Examination shows numerous 0.5- to 3-cm fluid-filled blisters.  A skin biopsy is performed, and microscopic findings are shown in the image below:

Which of the following is the most likely diagnosis?

A 38-year-old woman comes to the urgent care clinic with a 2-day history of sore throat.  It is associated with fever and cervical lymphadenopathy, but not rhinorrhea, sneezing, or coughing.  On examination, erythema and edema involving the posterior pharynx and a purulent tonsillar exudate are present.  Rapid bedside streptococcal antigen testing is positive, and the patient is started on oral penicillin V.  She returns the following day with a pruritic skin rash that came on suddenly after starting the antibiotic.  The skin lesions observed on physical examination are shown in the image below.

What is the most likely finding on biopsy of these lesions?

A 28-year-old woman is brought to the emergency department by her family due to acute left flank pain.  The pain radiates to her groin and is associated with pink hematuria and urinary urgency.  Past medical history is unremarkable, and the patient has never experienced similar symptoms.  CT scan of the urinary system confirms the presence of a stone at the ureterovesical junction.  The patient is given intravenous morphine sulfate for pain relief.  Fifteen minutes later, she develops diffuse itching involving the arms, legs, and back.  Which of the following is the most likely mechanism causing this patient’s adverse reaction?

A 35-year-old man comes to the office for evaluation of red skin lesions under his nipple that were first noticed by his wife.  The lesions are not itchy or painful, and no other family members have skin lesions.  He has not used any new soaps, lotions, or detergents.  The patient has no known medical problems and takes no medications.  He drinks 4-6 beers every night.  He does not use tobacco or illicit drugs.  Body mass index is 32kg/m2, and vital signs are normal.  Skin findings are shown below.

Which of the following is the most likely diagnosis?

A 63-year-old woman comes to the office for a routine preventive examination.  She has no significant medical problems and takes no medications.  The patient consumes a balanced diet; gets regular exercise; and does not use tobacco, alcohol, or illicit drugs.  She is up to date on breast, colon, cervical, and lipid screenings.  Her physical examination findings are unremarkable.  The patient expresses concern about wrinkles around her eyes that make her “look old.”  A decrease in which of the following is most likely responsible for this patient’s complaint?

A 27-year-old woman comes to the emergency department with a 1-day history of skin rash.  Two weeks ago, she had an episode of recurrent genital lesions, which began with small papules and subsequently became vesicular with ulceration, crusting, and eventual healing.  The patient has no other medical conditions and takes no medications.  On physical examination, she appears comfortable.  Temperature is 37 C (98.6 F).  She has small linear erosions in the oral mucosa.  Skin findings are shown in the image below.

Which of the following is the most likely diagnosis?

A 35-year-old man comes to the office for evaluation of a rash on his elbows.  The patient has had the rash intermittently for several months, but lately, it has become more persistent and bothersome.  He also describes mild associated itching but no pain, and use of topical moisturizing lotion does not provide relief.  The patient installs tile floors for a residential construction company.  He has no chronic medical conditions and takes no regular medications.  The patient does not use tobacco, alcohol, or recreational drugs.  Vital signs are within normal limits.  The rash on his elbow is shown in the image below, and a similar rash is present on the other elbow.

Which of the following histologic changes are most likely to be found in this patient’s skin lesions?

A 12-year-old boy is brought to the office due to a week of nonproductive cough and rash.  He has also had low-grade fevers, malaise, and headaches.  The patient has no prior medical conditions and is up to date with immunizations.  Lung examination reveals bilateral crackles and wheezes.  There is a diffuse rash on his torso and extremities as shown in the exhibit.  Which of the following is the most likely cause of this patient’s skin lesions?

A 17-year-old boy comes to the office for evaluation of a rash.  For the past 2 years, the patient has had recurrent skin bumps that are frequently red and painful.  He has no other medical conditions and takes no medications.  Vital signs are within normal limits.  Skin examination findings are shown below.

This patient’s skin condition primarily affects which of the following structures?

A 31-year-old woman comes to the physician with a velvety skin rash in her axilla, as shown in the image below.

Which of the following is the most likely cause of this patient’s condition?

A 65-year-old man comes to the office due to skin lesions on his back.  He first noted the spots 5 years ago and says they are becoming more numerous.  The lesions are occasionally pruritic but are otherwise asymptomatic; he is not bothered significantly by them and made today’s appointment at his wife’s insistence.  Medical history is notable for hypertension, hyperlipidemia, and type 2 diabetes mellitus.  On examination, there are numerous pigmented plaques, as shown in the image below.

Which of the following is the most likely diagnosis?