Background:Rhabdomyomatous mesenchymal hamartomas (RMHs), also termed striated muscle hamartomas, are rare benign tumors of skin and subcutis, which mostly occur at birth with a predilection for the head and neck. Simple surgical excision is the treatment modality of choice with excellent prognosis.Objective:To review the spectrum of the different clinical and pathologic features of RMHs in pediatric patients and recognize their characteristics to avoid confusion with other lesions in their list of differential diagnosis.Methods:Six cases of RMH diagnosed at our institution from 2009 to 2021 were retrieved from our files and reviewed retrospectively after anonymization by an honest broker. This review is IRB-approved by the University of Pittsburgh School of Medicine, study STUDY19080192.Results:The patients' age ranged from 6 days to 8 years, with a female predominance (2:1). In all cases, the lesion was present at birth. All lesions, except for 2, occurred in the head and neck regions. One patient had multiple additional small nodules in the face, whereas all others presented with solitary RMHs. The size of the lesions varied, and their composition included bundles of skeletal muscle (the landmark finding) associated with variable amounts of adipose, fibrous, vascular, nerve, and adnexal structures.Conclusions:RMH is a benign hamartomatous lesion with a variable phenotypic spectrum. RMHs predominate in the head and neck. Familiarity with these lesions, including their presentation in less frequent anatomical sites, is important to avoid diagnostic misinterpretations and potential overtreatment. This study represents one of the largest series of RMHs in the literature, including an unusual case in a perianal location.

Anaplasmosis with associated haemophagocytic lymphohistiocytosisA 76-year-old man presented with fever, altered mental status, malaise and respiratory distress. His initial blood count showed a platelet count of 60 9 10 9 /l, white blood cell count of 5Á5 9 10 9 /l, neutrophil count of 0Á9 9 10 9 /l and haemoglobin concentration of 144 g/l. A computed tomography scan showed hepatomegaly without splenomegaly. Ferritin was significantly elevated at 35 531 lg/l. His clinical status rapidly worsened, and he developed respiratory failure, requiring intubation, and acute kidney injury, with an elevated creatinine of 88 lmol/l and blood urea nitrogen of 35 mg/dl (normal range 6-24 mg/dl). The clinical picture and laboratory findings suggested the possibility of haemophagocytic lymphohistiocytosis (HLH), and a broad workup was initiated, including a bone marrow biopsy, for further evaluation and to attempt to identify any inciting factors. The peripheral blood film showed multiple neutrophils with basophilic intracytoplasmic inclusions strongly suggestive of the morulae seen with Anaplasma phagocytophilum infection (top images, 9100 objective). Further, the bone marrow aspirate identified increased histiocytes and with occasional haemophagocytic cells (bottom images, 9100). Additional tests showed triglycerides of 2Á1 mmol/l, soluble interleukin 2 level of 4912 µ/ml (normal range 137-838 µ/ml) and decreased NK-cell activity, diagnostic criteria for HLH being met. Anaplasma PCR was performed and was positive, confirming the diagnosis of anaplasmosis. The patient was started on intravenous doxycycline, resulting in rapid improvement of his clinical status with subsequent extubation, and he was eventually discharged clinically well.Anaplasmosis has rarely been reported in association with HLH. Here, the inability to obtain a detailed clinical history to assess for tick exposure and the prominent HLH-related features could have masked the underlying diagnosis. This case highlights the importance of recognising the classic peripheral blood findings of anaplasmosis, this being as a potential underlying cause of HLH.

No abstract

No abstract

No abstract

No abstract

No abstract

No abstract