Answer: (E) Unilateral duplicated collecting system

Live kidney donors are exposed to medical and surgical risk for the benefit of another without a countervailing personal medical benefit. As such, it is particularly important to be as sure as possible that the risk to the donor is minimal. Centers perform routine screening on all potential donors that includes the presence of medical disease, infection, malignancy, and procedure-specific risks. Hypertension or diabetes puts donors at a higher risk of future kidney disease; all centers consider hypertension a relative contraindication (and some consider it an absolute contraindication), and almost all centers consider diabetes an absolute contraindication. HIV predisposes a patient to developing HIV-associated nephropathy and as a result is considered an absolute contraindication to donation; furthermore, transplantation of organs infected with HIV currently violates congressional law. Current drug dependency is also at least a relative contraindication for donation. As surgical techniques evolve, comfort with anatomic variations such as multiple blood vessels or duplicated urinary collecting systems is increasing; currently, a duplicated urinary collecting system is not considered a contraindication.

Answer: (A) Early distant metastases

Merkel cell tumors are histologically similar to basal cell carcinomas but are both locally aggressive and commonly demonstrate distant metastases to nodes, viscera, and bone. On hematoxylin and eosin (H and E) staining, they appear as deeply basophilic cell clusters in the dermis with nuclei that do not demonstrate severe atypia. They may stain positive for enolase, allowing differentiation between Merkel cell tumors and basal cell carcinomas. In addition, using keratin antibodies, a distinct perinuclear dot pattern is seen with aggregation of antibodies at the nuclear border. CT or MRI should be used to evaluate for distant metastatic disease. They are difficult to treat, but common therapy consists of surgery (with 2- to 3-cm margins when possible), elective regional lymphadenectomy or sentinel lymph node biopsy, and radiation. Radiation therapy is useful as adjuvant therapy for both local and regional control and can also be used when surgery is not an option. Chemotherapy is currently under investigation.

Answer: (B) Cystic mass with overlying vesicles

Cutaneous lymphatic malformations often present as cystic masses with overlying vesicles. A lymphatic mass would not be associated with telangiectasias, it would not be nodular or pulsatile, and it would not be fixed to underlying tissues.

Answer: (E) Ureterocystostomy

Ureteral injuries are a common and feared complication of pelvic surgery. The common ways that ureters are injured include crushing injury by inadvertent clamping, electrocautery injury, and inadvertent resection as part of a specimen. In cases where the ureter is ligated, pressure hydronephrosis develops which can lead to urosepsis. In addition, the pressure can lead to necrosis of the remaining ureteral wall, which can rupture and allow urine to freely extravasate into the abdomen leading to urinoma formation.

The treatment of ureteral injury depends on the injury type. For minor injuries, where there is a partial transection, the ureter can be closed primarily over a stent. For complete transections, in which the ureter is completely transected, primary closure (ureteroureterostomy) should be attempted. In cases of injury below the pelvic brim, ureteroureterostomy can be difficult and a ureterocystostomy is the procedure of choice to re-establish continuity with the urinary tract.

Answer: (D) Superficial peroneal nerve

Fasciotomy of the four compartments of the lower leg may be performed through one or two skin incisions, although the two-incision technique is more common. The lateral incision is placed 2 cm anterior to the head of the fibula. Through this incision, the anterior and lateral compartments are released. The second incision is placed 2 cm posterior to the posterior medial edge of the tibia, releasing the superior and deep posterior compartments. Both incisions should span the length of the leg. The correct placement of these two incisions will leave an 8- to 10-cm skin bridge that will be unlikely to necrose.

Injury to the superficial peroneal nerve may occur while performing the lateral fasciotomy, as this nerve travels relatively superficially along the fascia between the anterior and lateral compartments.

The tibial and deep peroneal nerves are both deep to the incisions needed for fascial release, and less likely to be transected. The saphenous nerve travels along the lateral border of the tibia, and as such runs parallel and anterior to the posterior skin incision. The lateral femoral cutaneous nerve innervates the lateral aspect of the thigh.

Answer: (C) Surgical resection with 1-cm margin and primary repair

Surgical resection alone is appropriate for management of T1 lesions on the lips. However, radiation therapy alone has an equal outcome. A 1-cm margin should be taken and primary repair performed. Five-year survival is greater than 90%. If a T1 lesion is located in the labial commissure (corner of the lips), it can be treated with resection and immediate reconstruction. Radiation may be used as the sole modality of treatment for commissural lesions but presents unique challenges.

T2 and greater stage lesions on the lips should be treated with surgical excision and immediate reconstruction, followed by radiation therapy.

Of note, mental nerve invasion is associated with lymph node involvement in 80% of cases. The 5-year survival for these is 35%.

Tis: Carcinoma in situ

T1: Tumor ≤2 cm

T2: Tumor >2 cm but ≤4 cm

T3: Tumor >4 cm

T4: Tumor invading adjacent structures

Answer: (A) Axillary nerve

Anterior dislocation of the humeral head can occur when force is applied to an abducted arm, further extending it. These are classic “football injuries.” Anterior-posterior shoulder radiographs reveal the humeral head displaced inferior to the coracoid process and medial to the glenoid fossa. This injury is associated with tear of the anterior shoulder joint capsule, compression fracture of the humeral head posteriolaterally, and possible damage to the axillary nerve as it is stretched around the humeral neck. Axillary nerve deficit presents as sensory loss over the anterolateral aspect of the proximal shoulder.

Recurrent dislocations should be treated with surgical correction. Posterior dislocation is not associated with a specific nerve injury but with seizures. The sural nerve innervates the posterolateral aspect of the lower leg.

Answer: (B) Epithelial appendages and thickness of graft

Split-thickness skin grafts may be harvested from any surface of the body, but sites should be chosen that are easily concealed in clothing. Common sites include the upper anterior and lateral thigh. The buttocks may be used as a donor site, but the patient may require assistance caring for the wound. The scalp is used for resurfacing areas of the face too large for a full-thickness graft and is especially useful in severe burns with limited donor-site availability. Because of its thickness, scalp skin may be repeatedly harvested with almost no risk of alopecia or subsequent hair growth at the recipient site. For hand wounds, the upper inner arm is a cosmetically appealing donor site.

The donor site also must be dressed appropriately at the conclusion of a skin graft operation. Full-thickness donor sites closed primarily are dressed as are other wounds closed primarily. For split-thickness graft donor sites, achieving hemostasis can be facilitated with the application of a moist gauze containing epinephrine solution.

Donor sites for split-thickness grafts heal spontaneously from epithelial cells remaining in epithelial appendages within the dermis and at the wound edges. Healing begins within 24 hours of harvesting, and the rate of healing is directly proportional to the number of epithelial appendages remaining and inversely proportional to the thickness of graft harvested. When the epidermis has regenerated, it may be reharvested; however, each harvest may remove a portion of dermis that is not regenerated. The initial epithelium that is regenerated is very delicate and is easily disrupted by dressing changes. This is rationale to use a semi-occlusive dressing that does not need to be removed until healing is complete. Finally, hyperpigmentation may persist for many months following donor-site healing, and some individuals may develop hypertrophic scarring or even keloids at the site.

Answer: (E) Lower incidence of contractures

FTSGs have the advantage of lower incidence of contractures compared with STSGs. In addition, FTSGs from similar areas as the defect will afford superior color match compared to STSGs. For instance, periauricular skin serves as a close color match for a nasal defect. However, FTSGs have less resistance to infection than STSGs, and are generally less useful for coverage of large areas. Due to the nature of FTSGs, which have a higher nutritional demand and fewer cut vessels with which to absorb nutrients from the wound bed, they require more blood supply than STSGs. STSGs are generally more useful for coverage of larger wounds, bacterial-contaminated surfaces, and granulation bed.

Answer: (D) Take a biopsy of the tumor, close, and await the pathology report to plan open surgery

Ovarian cancer is the number one cause of death from a gynecologic malignancy in North America. Part of this fatality stems from late diagnosis, as most women present only after the cancer has spread well beyond their reproductive systems. Some cases are discovered only incidentally, as in this scenario.

In the setting described, it would be wisest to obtain a biopsy and end the operation. The surgical treatment of metastatic ovarian cancer mandates maximal debulking and possible multiorgan resection, as the extent of surgical debulking directly affects patient curability. For this reason, it is advisable to close the patient and discuss the implications and risks of the treatment, and possibilities such as permanent colostomy. The patient should also be referred to a gynecologic oncologist for primary surgery, as they are more experienced with disease-specific considerations such as the placement of an intraperitoneal port for intraperitoneal chemotherapy.

Intraoperatively, the goal of surgical debulking should be the removal of all visible tumor. If all visible tumor cannot be safely excised, then a surgical objective of leaving no residual tumor nodule measuring >1 cm in maximal diameter should be attempted. For women with advanced-stage epithelial ovarian cancer, overall survival is inversely proportional to the maximal diameter of residual disease, with patients left with no gross residual having the best survival outcome and chance of cure. Radical debulking may entail multiple bowel resections and removal of all pelvic contents en masse in an extraperitoneal, ventral-to-dorsal technique: Bladder, uterus, adnexae, and rectosigmoid. Splenectomy, omentectomy, hepatic resection, and diaphragm stripping may be warranted.
Some surgeons advocate second-look procedures to assess for further tumor, although the practice is controversial.

Answer: (B) Convert his fluids from LR to 3% normal saline

This young man is suffering from acute onset of the syndrome of inappropriate antidiuretic hormone (ADH) secretion (SIADH). This disorder is characterized by the unsolicited release of ADH independent of the body’s usual mechanisms for osmostat regulation. Acute onset of SIADH results in hyponatremia secondary to free water retention. Chronic SIADH results in hyponatremia secondary to free water retention and eventual volume expansion and natriuresis. SIADH does not affect the body’s ability to regulate sodium handling and intravascular volume.

Treatment of SIADH is centered upon free water restriction and, when necessary, salt administration. Careful monitoring of fluid status, urine output, and serum sodium is essential, such that over- or under-correction does not ensue. In the asymptomatic hyponatremic patient with chronic SIADH, free water restriction is the mainstay of therapy and is often sufficient by itself. In refractory cases of chronic SIADH, daily salt tablets and a loop diuretic (which lowers urine osmolality by direct interference with the countercurrent concentrating mechanism) are often the next best step. In the rare patient with chronic SIADH in whom the aforementioned interventions are not effective, agents that act directly on the collecting tubule to diminish its responsiveness to ADH—including demeclocycline (300 to 600 mg BID) and lithium—are considered.

In both acute and chronic SIADH, it is important to remember that—as a rough approximation—the osmolarity of fluid administered enterally and parenterally must exceed that of the urine for the serum sodium concentration to rise. The trauma patient described above is suffering from acute
onset of SIADH and is dependent on parenteral replacement of electrolytes and fluid. We are told his urine osmolarity is 548 mOsm/L. From this (remembering sodium handling and volume regulation remain intact), we can roughly approximate that the electrolytes he receives in every liter of LR (osmolarity of 274 mOsm/L) will be excreted in approximately 500 mL of urine. Thus, for every liter of LR he receives, he will retain 500 cm³ of free water at his present level of ADH release. Converting his IVF to 3% normal saline will provide him with 1,026 mOsm of electrolytes (513 mEq each of sodium and chloride) in every liter of fluid he is given. Assuming ADH release and urine osmolarity remain constant, he will excrete this volume of electrolytes in approximately 1,872 cm³ of fluid. In this manner, he will lose 872 cm³ of free water with every liter bolus of 3% normal saline he receives and his serum sodium level will rise appropriately.

The presence or absence of neurologic symptoms secondary to hyponatremia and the severity of these symptoms will help to determine the goal rate of correction. Overly rapid correction should be avoided, as it can result in central pontine myelinolysis.

Answer: (B) Closed reduction and internal fixation

Unlike adults, supracondylar fractures are common in children. A supracondylar fracture is located on the humerus, proximal to the growth plate. Management of these fractures depends on the severity of the injury. The Gartland classification exists for characterization of supracondylar fractures. Specifically, Gartland type I fractures are nondisplaced, Gartland type II fractures are partially displaced, and Gartland type III are totally displaced. For nondisplaced fractures, conservative treatment (casting and immobilization) is sufficient. However, for displaced fractures, closed reduction and percutaneous pin fixation in the operating room is necessary to ensure a proper reduction and stabilization.

Answer: (D) Poor motor score component of the GCS