Case of the Week: May 1-May 8, 2003
History: 2 month old infant with a hard lump on the head.
(Click for a larger image.)
Diagnosis: DIAGNOSIS: Cephalhematoma
The skull radiograph demonstrates a rim of calcification in the periphery of a raised swelling on the left parietal bone. This finding is characteristic of a cephalhematoma in its healing stages.
Usually seen in association with birth trauma, the cephalhematoma represents subperiosteal hemorrhage. The periosteum of the involved bone, usually parietal or occipital bone, is elevated by the underlying hematoma. Therefore, the hematoma is sharply limited by the margins of the bone and does not cross suture lines. In its earliest stages (first 2 weeks), the hematoma is of soft tissue density due to its blood contents. Early skull films (during the first two weeks) will show the swelling as a soft tissue "mass" which is limited at its margins by the cranial sutures (below).
As healing progresses, there is formation of a shell of bone by the elevated periosteum and the calcification becomes visible radiographically, as in this case. It initially appears as a thin calcified shell at approximately 2 weeks, covering the hematoma, and the layer of calcification subsequently thickens as it matures. This week's "unknown" case demonstrated the appearance at approximately 2 months. The later sequelae, following complete resorption of hematoma, result in incorporation of the calcified rim into the outer table of the skull. This may persists for months or years as a palpable (and radiographically visible) thickening of the outer table of the skull.
Subtle skull fractures underlying the cephalhematoma may coexist but are usually not clinically significant.
In the neonate, swelling of the scalp may also be seen with caput succedaneum (subcutaneous edema and/or hemorrhage) and subgaleal hemorrhage (subaponeurotic hemorrhage). These two conditions are more superficial and extend more widely over the skull because they are not limited by the attachments of the periosteum.
In the older infant and child, sequelae of cephalhematoma may cause confusion. Asymmetry of the skull or palpable bulge at the site of the calcified cephalhematoma may cause clinical concern for a skull mass or craniosynostosis. Skull radiography will usually demonstrate the
characteristic smooth thickening resulting from an old calcified cephalhematoma. The findings may persist for years, even into adulthood. A cyst-like radiolucent lesion at the site of old cephalhematoma may also persist, and this entity should be kept in mind when evaluating cyst-like skull lesions.
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