A new differential diagnosis of the skin rashes along the ventriculoperitoneal shunt: Do no harm to the patient

Dear Editor, Ventriculoperitoneal shunt (VPS) placement stands as one of the most common neurosurgical interventions and remains a mainstream therapy for hydrocephalus.[1] When assessing skin rashes along the VPS tract following surgery, common differential diagnoses encompass VPS infection and VPS hypersensitivity reaction.[1,2] Removal of the shunting tube is the standard treatment for VPS infection and VPS hypersensitivity reaction.[1,2] Herein, we presented an alternative diagnosis for linear rashes along the VPS: VPS placement-associated traumatic purpura, which has not been published until now. The common etiologies of the skin rashes along the VPS tract with the corresponding characteristics, diagnostic methods, and treatments were summarized in this article. Timely diagnosis can avoid unnecessary extensive investigations as well as invasive treatments. A 17-year-old male with the underlying diseases of cerebral palsy, epilepsy, and hydrocephalus presented with sudden-onset linear rashes on the anterior trunk 2 days following VPS revision surgery for VPS obstruction. VPS placement surgery was performed at the age of 5 months for hydrocephalus, and the patient has undergone several VPS revisions due to VPS malfunction since then. The patient took long-term medications of piracetam and levetiracetam at a dosage of 200 mg/day and 600 mg/day, respectively, for epilepsy. Physical examination showed well-demarcated, linear, erythematous-to-purpuric maculopatches along the shunt tract, extending from the abdominal incision wound to the right neck [Figure 1a]. These lesions did not show blanching upon diascopy. No topical medications or dressings had been applied to the affected skin previously. The patient remained afebrile, experienced no pain or pruritus, and the affected skin did not exhibit swelling or warmth. Laboratory analyses of serum showed normal leukocyte counts, eosinophil counts, platelet counts, international normalized ratio, activated partial thromboplastin time, and prothrombin time. Cerebrospinal fluid (CSF) analysis revealed normal leukocyte and eosinophil counts. No pathogens were isolated from either CSF or blood cultures. The pediatric surgeon reported difficulties in VPS placement with multiple attempts during VPS revision this time. The erythematous-to-purpuric maculopatches turned into a yellowish-brownish hue by the 5th day, indicative of resolving ecchymoses [Figure 1b]. VPS placement-associated traumatic purpura was diagnosed by exclusion.Figure 1: Ventriculoperitoneal shunt placement-associated traumatic purpura. (a) Linear, nonblanchable, erythematous-to-purpuric maculopatches along the shunt tract. (b) The ecchymoses resolving into a yellowish-brownish hue on the 5th day.The common etiologies of the skin rashes associated with the VPS tract in the literature are summarized in Table 1, including VPS infection and VPS hypersensitivity reaction. Approximately 70% of VPS infections develop within 1 month and 90% within 6 months, with coagulase-negative Staphylococci, Staphylococcus aureus, Propionibacterium acnes, and diphtheroids being the most common microorganisms.[1,3,4] Associated symptoms/signs include fever, headache, neck stiffness, malaise, and elevation of inflammatory markers (e.g. erythrocyte sedimentation rate, C-reactive protein, and lactate).[1,3,4] The diagnostic criteria involve pathogens isolated from ventricular fluid, lumbar CSF, or blood, or the presence of CSF pleocytosis (≥50 white blood cells/mm3) in combination with at least one of the following: fever, shunt malfunction, neurologic symptoms, or abdominal symptoms.[1,4] VPS hypersensitivity reaction is a rare type IV delayed hypersensitivity reaction to silicone, typically occurring within 2–7 days after exposure.[2,5] It may be accompanied with gastrointestinal discomfort and peritonitis.[2,5] Laboratory findings commonly entail lymphocytic CSF leukocytosis, sterile CSF, peripheral or CSF eosinophilia, and fibrotic reaction with aggregation of eosinophils and giant cells in the tissue surrounding the used shunt.[2,5] Patch testing or anti-silicone antibody examination can provide additional diagnostic assistance.[2,5]Table 1: Common differential diagnoses of linear rashes along the ventriculoperitoneal shuntTraumatic purpuric eruptions are not uncommon in children.[6] These skin eruptions are not always recognized due to an initial presentation as erythema, then intensifying within hours or days to become purpura, and ultimately turning brownish, hyperpigmented in the late stage.[6] However, the skin lesions should remain nonblanchable in diascopic examination, even at the early stages.[6] The extravasation of red blood cells into the dermis gives rise to purpura.[6] Various intravascular, vascular, and extravascular factors, such as coagulopathy, increased capillary fragility, and skin atrophy associated with long-term corticosteroids use, respectively, may contribute to traumatic purpura. In this case, thinner pediatric skin, reduced hemostasis associated with long-term piracetam use,[7] surrounding tissue fibrosis and wound adhesions resulting from a history of repeated VPS revisions, and technical difficulties in coursing the shunt superficially in the subcutaneous layer, may contribute together to this condition. VPS placement-associated traumatic purpura is self-limited. Differential diagnoses from VPS infection and VPS hypersensitivity reaction are crucial for that aggressive treatments including VPS removal and VPS replacement with silicone-free hypoallergenic shunt are recommended, respectively.[1-4] The physical examination by palpation to differentiate between blanchable and nonblanchable erythemas should not be overlooked. Early, correct diagnosis of the skin rashes associated with VPS can avoid unnecessary investigations and invasive treatments. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent form. In the form, the guardians has given their consent for the images and other clinical information to be reported in the journal. The guardians understand that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed. Data availability statement The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.