====== Skull osteomyelitis from a infected pilar cyst ======

//J.Sales-Llopis//

//Neurosurgery Service, Alicante University General Hospital, Alicante, Spain.//
----

----
The patient is an 86-year-old male with a history of [[high blood pressure]], [[dyslipidemia]], and [[chronic ischemic heart disease]]. He was taking [[rivaroxaban]] for [[deep vein thrombosis]]. Additionally, he has been experiencing [[complication]]s related to a supposedly infected [[trichilemmal cyst]] in the [[occipital region]] of the [[scalp]] for the past 5 months. The [[cyst]] was drained, but there has been ongoing bleeding and [[pus]] discharge from the [[wound]], with a lack of continuity in the [[skull]] cap at the surgical site.

{{::pilar_cyst_complication_osteomyelitis.jpg?300|}}

On CT imaging, a subcutaneous extracranial lesion is observed on the right occipital level, exhibiting heterogeneity with air presence and loss of skin integrity. The lesion has caused erosion of the underlying bone and is similar in size to a previous study.[[Skull osteomyelitis]]. No signs of hemorrhage or space-occupying lesions are noted. However, there is diffuse hypodensity of the periventricular white matter, indicating moderate/severe chronic small vessel ischemic disease. The patient also exhibits increased ventricular size, possibly suggestive of normal pressure hydrocephalus, which should be clinically evaluated. The midline is centered, and basal cisterns are clear.

In addition, the patient's exudate shows the presence of [[Proteus mirabilis]], pending confirmation of its resistance to [[ertapenem]]. The organism is susceptible to [[amoxicillin]]/[[clavulanate]], [[meropenem]], [[amikacin]], and [[quinolone]]s. [[Klebsiella oxytoca]] is also present, which is susceptible to [[amoxicillin]]/[[clavulanate]], [[cefotaxime]], [[carbapenem]]s, [[quinolone]]s, and [[trimethoprim]]/[[sulfamethoxazole]]. The patient is currently receiving a combination of [[cloxacillin]] and [[ceftazidime]] antibiotics, with an urgent meropenem dose scheduled.

Furthermore, the patient's bloodwork shows [[macrocytosis]], indicating the presence of abnormally large red blood cells.