Air/gas outside the aero-digestive tract is abnormal; depending on its location, it is usually called emphysema, referring to trapped air/gas in tissues, or ectopic air/gas. It can be associated to a wide range of disorders, and although it usually is an innocuous condition, it should prompt a search for the underlying aetiology, since some of its causes impose an urgent treatment. In rare instances, it may itself represent a life-threatening condition, depending on the site involved and how quickly it evolves. Abnormal air/gas beyond viscera and serosal spaces, reaches its location following some anatomic boundaries, such as fascia, which may help search the source; however if the air pressure exceeds the strength of the tissues, or the time between the aggression and the imaging is too long, the air/gas is almost everywhere, which may hinder its cause. Good knowledge of the anatomic spaces and how they connect between them facilitates the quick detection of the cause.Teaching points• Ectopic air can be depicted on conventional radiographs; but CT is more sensitive and accurate• Visceral and retropharyngeal spaces directly communicate with mediastinum• Renal fascia is a single multilaminated structure, which contains potential space

Solitary fibrous tumor (SFT) is a rare type of soft tissue neoplasia, usually seen in adults. They are mesenchymal neoplasias that appear to exhibit fibroblastic differentiation, classically described in the pleura, but can arise anywhere. They have a generally benign course; however, in rare cases, they may recur locally or at a distance. When surgery is not possible or in the presence of metastasis, chemotherapy or palliative radiotherapy may be therapeutic options. The patient was a 44-year-old man, a construction worker, healthy apart from a totally resected left pelvic SFT 3 years before. He was observed over the last several times in the emergency department (ED) by right sciatic pain and discharged. He had no history of trauma. A lumbar MRI was performed without alterations of relief. The worsening of the symptomatology, with commitment of the autonomous march, resorted him again to ED. Clinical features showed grade 2 strength with hypoesthesia and an aquiline reflex abolished in the right lower limb (MI) and strength grade 4+ at the distal level of the left MI. There was a palpable rounded swelling on the posterior aspect of the right thigh (5 × 8 cm), with an elastic and non-painful consistency at palpation. MRI of the neuro-axis showed no changes of relief. Pelvic CT showed swelling with soft tissue component, which invaded the iliac bilaterally and right sacroiliac joint, with lithic alteration. The histology of the pelvic lesion and thigh lesion revealed an SFT. Radiotherapy and then chemotherapy were performed. The patient died 1 year after the diagnosis. We report a fatal case of recurrence of SFT. The authors highlight the case because of its rarity and its "malignant" evolution. Long-term follow-up of these patients is required because of the risk of recurrence of these tumors and their uncertain biological behavior.

Introduction: Kikuchi–Fujimoto disease (KFD) was originally described in a young woman and is a rare, benign and self-limited condition of unknown cause, usually characterized by cervical lymphadenopathy and fever. The diagnosis of KFD is made by lymph node biopsy and treatment is only symptomatic, with signs and symptoms usually resolving within one to six months. Case Report: A 31-year-old female, rabbit breeder, presented with complaints of fever, facial and hand skin lesions for 10 days. Physical examination revealed nose, malar, scalp, fingers and pinna erythematous papules; also painful bilateral cervical and axillary lymphadenopathy. Laboratory studies showed normocytic/normochromic anemia (hemoglobin 10.4 g/dL), leukopenia (white blood cell count 2.2x103 u/L), neutropenia 44.4% and elevated erythrocyte sedimentation rate 31 mm/h. Serology for infectious agents, microbiology and autoimmune blood work studies were negative. Computed tomography scan of the neck revealed small cervical lymphadenopathy and enlarged axillary lymphadenopathy. She underwent biopsy of a right axillary lymph node, which revealed Kikuchi lymphadenitis xanthomatous type. Skin biopsy showed unspecified perivascular lymphocytic infiltrate. On a three-month follow-up visit, she continued to be afebrile, had improved white cell blood count and had only small right axillary lymphadenopathy visible on ultrasound. Skin lesions had disappeared. Conclusion: Kikuchi-Fujimoto disease should be considered in the differential diagnosis when a young woman presents with fever and cervical lymphadenopathy. Despite its benign and self-limited nature, patients should be followed for a few years since recurrence is common and some patients may develop autoimmune disorders.