Table 2 Clinical and radiological aspects of soft tissue infectious, inflammatory, and congenital lesions in children
| Â | Â | Clinical and histological aspect: | Findings in CT scan and MRI | |
|---|---|---|---|---|
• Inflammatory process of the skin and subcutaneous space • Diffuse neutrophil infiltration • Gram-positive cocci generally | • Ill-defined curvilinear or linear areas, with low signal intensity on T1-weighted images, and high signal T2 weighted, associated with reticular appearance in the subcutaneous space • Muscle and bone marrow signals are normal • The presence of fluid collection is not pathognomonic | |||
• Focal collection, necrotic material • Hematogenous or local dissemination | • Well-defined focal collection with low T1 signal and high T2-weighted images • Enhancement of the surrounding rim after intravenous administration of gadolinium • The signal’s intensity varies depending on cellular content • Soft tissue edema does not indicate the extension of infection to these structures | |||
• Rapidly progressive infection • Extensive necrosis of subcutaneous tissue dissecting along fascias • Streptococcus serogroup A. Anaerobes, Staphylococcus | • Intermediate to low signal intensity, on T1-weighted images, with variable enhancement after gadolinium administration • T2 weighted presents a high signal intensity with thickening of all the compartments • Involvement of deep fascia and intramuscular compartments | |||
• Primary bacterial infection of the skeletal muscle • Immunodeficiency • Staphylococcus in 90% of cases | • Primary bacterial infection of skeletal muscle, endemic in tropics, generally in HIV patients • T1-weighted images show increase in volume and subtle increased signal than normal muscle. Enhancement of the rim after gadolinium injection is usual • A focal hyperintense area is generally observed on T2 weighted images, with hypointense peripheral rim | |||
• Generally in lateral compartment of neck • Could invade other structures | • There is no specific radiological aspect of soft tissue tuberculosis | |||
Malformative lesions | Vascular malformations | • May be clearly pulsatile • May hemorrhage or cause ulceration | • Low signals on both T1- and T2-weighted images due to high flow, serpiginous, the caliber varies. Little mass effect on adjacent structures | |
Capillary malformations [6] | • Involve epidermal and dermal layers • Port-wine stain | • Broad very shallow tissue abnormalities involving dermis and epidermis • T1 signal is similar to adjacent muscle and could interrupt subcutaneous tissue • High signal in T2and gadolinium administration | ||
• Are the most frequent • May be deep with overlying normal skin • Painful, distended with activity | • T1 similar to or lower than muscular signal • T2 weighting shows an intensely bright signal. (very slow flow). Remain bright after fat suppression • Lobular lesion, grapes-like lesion, with significant mass effect | |||
• May be local or diffuse • Involve epidermis and dermis, could be seen in mucosa of oral cavity or tongue | • MRI appearance is similar to venous malformations. Have significant mass effect • T1 low signal or similar signal to adjacent muscle interrupts subcutaneous tissues • T2 is intensely bright • Multiple filled fluid caverns or sinusoid structures | |||
• May be superficial or deep | • T1 signal low or similar to adjacent muscle • T2 moderate increase in signal, less bright and more heterogeneous, irregular shapes grapes-like | |||
First arch malformations [8] | Parotid, external auditory canal | Usually, branchial cleft anomalies are imaged with MRI with contrast. If an overt pit or fistula is evident on examination and amenable to cannulation, then CT neck with fistulogram and 3-dimensional reformatting is preferred | ||
Second arch malformations [8] | • Unilateral and right-sided presentations are most common • Is the most common, for which the differential diagnosis includes lymphatic malformation and cervical thymic cyst • In the anterior triangle of the neck, anterior to the sternocleidomastoid muscles. Anterolateral to the great vessels of the neck and may be adherent to the internal jugular vein or possibly protrude between the internal and external carotid arteries | |||
Third arch malformations [8] | • Left posterior cervical triangle | |||
Fourth arch malformations [8] | • 1–4% of all branchial cleft anomalies • Generally left sided • The pattern could appear from the pyriform sinus and courses through the thyrohyoid membrane to dive into the mediastinum along the tracheoesophageal groove • Endoscopic exam: Fistula in piriform sinus | |||
• Embryologic structure and can be found anywhere along the course of the thyroglossal duct, from the foramen cecum at the base of the tongue to the pyramidal lobe of the thyroid gland | Ultrasound aspect shows a well-circumscribed hypo- or anechoic cystic structure with posterior acoustic enhancement. Septa and debris or internal echoes from protein material, may be present in the absence of infection In the presence of infection, thickened and irregular cyst wall with increased peripheral vascularity may be present. A soft-tissue mass associated with a TDC may represent ectopic thyroid rests or, rarely, a carcinoma | |||
|  | Epidermoid, dermoid, and teratoid cysts [7] | • Well-defined mass | CT: epidermoid cysts have fluid attenuation; dermoid cysts have a more complex appearance, typically fat attenuation MR imaging: epidermoid cysts are T1 hypointense and T2 hyperintense; dermoid cysts are T1 hyperintense and T2 hypointense | |
Inflammatory lesions: histological aspect is key to establish differential diagnoses [9] | Langerhans cell histiocytosis. (eosinophilic granuloma) | Infectious: nontuberculous mycobacteria (lepromatous forms), Leishmania spp., and others Noninfectious: single system and multicentric system histiocytoses (Table 3) | • CT: scan enhancing soft-tissue masses with surrounding osseous erosion • T1: Hypointense, to isointense • T2: Hyperintense diffuse enhancement | |
Non-necrotizing granulomas | • Infectious • Auto-immune • Toxic • Drug: Bacillus et Guérin (BCG) inoculation • Other | No specific radiological aspect | ||
Necrotizing granulomas | Infectious: Mycobacterium tuberculosis, nontuberculous mycobacteria, brucellose, Aspergillus spp. Auto-immune: rheumatoid nodule | |||
Suppurative granulomas | Infectious: nontuberculosis mycobacterium | |||
Foreign body | Suture, starch | |||