Cutaneous findings in a case of Mediterranean spotless fever due to Rickettsia conorii, with gangrene of multiple toes.

Mediterranean spotted fever (MSF) is a tick-borne disease caused by Rickettsia conorii conorii. Some rare cases present without a rash, and they are known as "spotless." This fact is important; although the mortality rates for MSF are low and generally range from 0% to 3%, the absence of a rash usually leads to a delay in the diagnosis and, therefore, an increase in the rates of morbidity and mortality. Necrosis of the digits is one of the complications of MSF that has occasionally been reported in the literature. However, very few reports have studied the morphological changes seen in the cutaneous necrotic lesions. In this report, we describe the morphological changes found through examining a biopsy taken from a necrotic cutaneous lesion in a 69-year-old man who had been diagnosed with Mediterranean spotless fever due to R. conorii. The main morphological changes included areas of collagen degeneration in the papillary dermis, necrotic eccrine glands, and hypodermal collagen with a smudged homogeneous appearance.