MKSAP quiz: Loss of vision in one eye

This month's quiz asks readers to evaluate a patient with total loss of vision in the left eye, a 2-week history of sinus pain and rhinorrhea, and poorly controlled type 1 diabetes.

A 41-year-old woman is evaluated in the emergency department for total loss of vision in the left eye. She also reports a 3-day history of left-sided tunnel vision and a 2-week history of sinus pain and rhinorrhea. The patient has a 20-year history of type 1 diabetes mellitus, which has been poorly controlled for the past 18 months. Medications are insulin glargine and insulin aspart.

On physical examination, temperature is 37.2 °C (99.0 °F), blood pressure is 140/66 mm Hg, pulse rate is 110/min, and respiration rate is 18/min. Left eye proptosis and chemosis are noted; the left pupil is nonreactive. The left nasal mucosa has gray-black exudate and an eschar. A 2- × 3-cm black eschar is seen on the hard palate. Neurologic examination shows occulomotor, trochlear, trigeminal, and abducens nerve (cranial nerves III, IV, V, and VI) palsy on the left.

A CT scan of the head without contrast shows a mass in the maxillary sinus with extension into the left frontal lobe and surrounding edema.

Which of the following is the most likely diagnosis?

A. Anthrax
B. Aspergillosis
C. Lemierre syndrome
D. Mucormycosis

MKSAP Answer and Critique

The correct answer is D. Mucormycosis. This item is available to MKSAP 18 subscribers as item 108 in the Infectious Disease section. More information about MKSAP 18 is available online.

This patient has mucormycosis (rhinocerebral form), which has a mortality rate of 60% to 80%. Various organisms are responsible for causing mucormycosis, with Rhizopus and Mucor species being the most common. Patients with uncontrolled diabetes or ketoacidosis have a unique susceptibility. Other risk factors include immunocompromise from hematologic malignancies, organ transplantation, and cancer chemotherapy. The most common presentation is rhinocerebral. This is a rapidly fatal infection that spreads from the sinuses retro-orbitally to the central nervous system. Symptoms and signs include headache, epistaxis, and ocular findings, including proptosis, periorbital edema, and decreased vision. A pathognomonic finding on physical examination is the presence of a black eschar on the nose or palate. Mucormycosis is diagnosed by tissue biopsy and culture. The most important step in managing any form of mucormycosis is early, extensive, and repeated debridement of infected and necrotic tissue. The drug of choice is high-dose liposomal amphotericin B.

Cutaneous anthrax is the most common type of anthrax in the United States and results after causative microorganisms are introduced into a skin abrasion or open wound. Cutaneous lesions are initially pruritic and painless and subsequently progress to vesicular lesions surrounded by nonpitting edema. The lesions then become hemorrhagic or necrotic, and satellite lesions may form. Finally, a central black eschar can develop and usually resolves over 6 weeks. Anthrax does not cause rhinocerebral infection.

Rhinocerebral aspergillosis has a similar presentation to mucormycosis. A helpful clue to the correct diagnosis is the propensity of rhinocerebral aspergillosis to occur in patients with neutropenia, typically secondary to hematologic malignancy. In contrast, mucormycosis occurs most commonly in those with diabetes mellitus, especially with ketoacidosis, and typically is distinguished by the presence of the characteristic eschar. A biopsy is necessary to establish the correct diagnosis, which is important because treatment of the two conditions is different.

Lemierre syndrome (jugular vein suppurative thrombophlebitis) is a rare complication of acute pharyngitis that involves septic thrombosis of the internal jugular vein and bacteremia, typically involving Fusobacterium necrophorum. Lemierre syndrome should be considered in patients with antecedent pharyngitis and persistent fever despite antibiotic treatment. Soft-tissue CT of the neck with contrast typically shows a jugular vein thrombus with surrounding tissue enhancement. This disorder is not associated with necrotic involvement of the nose and sinuses.

Key Point

  • Rhinocerebral mucormycosis is a rapidly fatal infection that spreads from the sinuses retro-orbitally to the central nervous system in immunocompromised patients, especially those with uncontrolled diabetes or ketoacidosis; a pathognomonic finding on physical examination of the nose or palate is the presence of a black eschar.