Atlanto-axial Dissociation and Cervical Hyperextension
Joseph Junewick, MD FACR
over 7 years ago
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Heather Borders, MD
|Diagnostic Category: Developmental or Congenital
|Created: over 7 years ago
|Updated: over 7 years ago
12 month old female with vague area of swelling in the right labia that had been present since birth with intermittent fluctuation in size.
Fibrous Hamartoma of infancy of the labia
The area was excised and sent to pathology.
Vague area of abnormal echogenicity in the right labia with peripheral hypoechoic area and central relatively hyperechoic area. Vascularity was present on color doppler but was not significantly increased.
Fibrous hamartoma of infancy is a rare, benign soft tissue tumor that typically occurs within the first two years of life. It is most commonly found in the axilla, shoulder, inguinal region, and chest wall and is usually a solitary malformation located in the subcutaneous tissue or dermis. Local recurrence is uncommon and treatment is largely successful by local excision.
The lesions are typically 1 to 8 cm in diameter but have been reported up to 10 cm. The tumor is usually firm and may be affixed to underlying tissue, thus causing concern of potential malignancy.
Fibrous hamartoma is composed of three elements; fibrous tissue, adipocytes and primitive mesenchymal cells. Ultrasound is typicaly non specific and may be useful in excluding hernia. MRI may show stripes of mixed signal tissue and heterogeneous enhancment. The fibrous component appears as areas of low signal intensity on both T1- and T2-weighted images and the fatty component shows characteristic high signal intensity on both T1- and T2-weighted images. It has been suggested that the demonstration of subcutaneous trabeculae of fibrous tissue interspersed with fat in an organized pattern is strongly suggestive of fibrous hamartoma of infancy in the appropriate clinical setting.
Recognition of fat within the lesion, if MRI is performed, helps to narrow the differential diagnosis. At the age of presentation for these tumors a differential for fat containing lesions on MRI should include fibrous hamartoma, lipoma, lipoblastoma, and involuting hemangioma.
A differential for a vague mass in the labia in an infant could include; lymphadenopathy, hernia/ovary, hemangioma, vasular/lymphatic malformation, fibrous hamartoma or more aggressive lesions. An MRI could be done for further characterization.
In this case, an MRI was not done. The lesion was resected and shown to be a fibrous hamartoma of infancy.
Pediatric and Adolescent Musculoskeletal MRI; A case based approach.
Pediatric Soft tissue tumors. July 2009 RadioGraphics, 29, e36.