Diagnostic Puzzlers – systemic melanosis – bacteremia as the cause of pneumonia
Challenging cases to test your clinical skills
Case 1. Why the slate-gray skin?
A 34-year-old man who had progressive fatigue, anorexia, and blue discoloration of the skin for 6 weeks was referred to our center. Previously, at a local hospital, he underwent extensive evaluation for cyanosis, which included arterial blood gas analysis, hemoglobin electrophoresis, methemoglobin and sulfhemoglobin measurements, and right heart catheterization. No source for the cyanosis was found.
Physical examination was most notable for hepatomegaly and a “slate-gray” appearance of the skin (A). A skin biopsy specimen is also shown (B). What do you suspect?
Case 2. A rare cause of pneumonia
A 26-year-old man presented to an emergency department in Ioannina, Greece, with persistent fever for 1 week and rigors, nocturnal perspiration, and nonproductive cough. His chest film was consistent with lobar pneumonia.
What do you suspect is causing the pneumonia? How would you proceed?
Case 1. Why the slate-gray skin? The salient features of this case are the negative workup for cyanosis and the uniform homogeneous “slate-gray” appearance of the patient’s skin.
Skin biopsy specimens were remarkable for a profusion of melanin-laden melanocytes (B, arrows), which is consistent with a diagnosis of systemic melanosis. Subsequently, it was determined that the patient had had a melanoma excised from his right posterior neck 2 years earlier. Depth of resection and surgical margins were adequate at the time. Unfortunately, the man died 4 days after referral to our hospital.
(Case courtesy of Dr Jeffrey E. Weiland of Columbus, Ohio.)
Case 2. A rare cause of pneumonia: Blood cultures confirmed the diagnosis of acute infection with Brucella melitensis, a species found in healthy and diseased goats and sheep. Although brucellosis is still prevalent in developing countries, pulmonary complications are rare. Cough is a common symptom, but manifestations such as pneumonia, pneumonitis, granuloma, abscess, and pleurisy are present in fewer than 1% of patients. 
Radiographic abnormalities have been reported in 1% to 16% of patients with brucellosis, but these abnormalities usually resemble miliary tuberculosis, pneumoconiosis, or tumors.  Most of these findings have surfaced in subacute or chronic brucellosis  and are frequently attributed to inadequate duration of treatment. Lobar pneumonia as a chest radiographic finding is extremely rare; in countries in which B melitensis is endemic, it could be underdiagnosed or mistaken for atypical pneumonia.
In this case, bacteremia appears to be the cause of the pulmonary localization, although aerosol inhalation has frequently been cited as a possible route of brucella localization to the lungs.
Drs Akritidis, Mastora, and Pappas report that B melitensis is highly endemic to city dwellers in Ioannina; they presume that this patient was infected by drinking raw, unpasteurized milk. The patient was treated with tetracycline, 500 mg/d, and rifampicin, 900 mg/d, for 4 weeks.
Although one might expect hilar lymph nodes to be a more common site, because of brucella’s typical involvement with the reticuloendothelial system, this case suggests that unusual localizations of brucellosis should be considered in the differential diagnosis of pulmonary lesions in areas where brucella is endemic.
(case courtesy of Drs Nikolaos Akritids, Maria Mastora, and Georgios Pappas of Peripheral General Hospital G. Hatzikosta,” loannina, Greece.)
(1.) Lubani MM, Lutu AR, Araj GF, et al. Pulmonary brucellosis. QJ Med. 1989;264:319-324.
(2.) Sanford JP. Brucella pneumonia. Semin Respir Infect. 1997;12:24-27.
(3.) Patel PJ, AI-Suhaibani H, AI-Aska AK, et al. The cheat radiograph in brucellosis. Clin Radiol. 1988;319:39-41.
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