PATHOLOGY FINDINGS:
GROSS:
The operative specimen consisted of a sausage-shaped (3.5x2.0x1.2 cm), thinly-encapsulated mass of reddish-brown tissue (Fig 4). The cut surface has a mottled, vaguely nodular, homogeneous yellowish-brown appearance (Fig 5).
MICRO:
Microscopic examination of intra-operative smear (Fig 6), and paraffin sections (Fig 7 and Fig 8), shows the mass to be composed of sheets of hematopoeitic elements (Fig 9), including myeloid, red cell and megakaryocytic lines, the latter showing Factor 8-related Ag positivity (Fig 10). Special stains reveal an intense background angio-architecture of small, branching capillary-sized vessels (Fig 11).
PATHOLOGY/IMAGING CORRELATION:
MR scan signal attributes correlate with homogeneous cellularity (T1 isointensity) and abundant interstitial water separating the cells (T2 hyperintensity). Strong diffuse enhancement may be inferred from the numerous capillaries.