Fig. 5: Diffuse venous malformation. Note bluish discoloration of left leg. Coronal T2W FS image reveals diffuse lower extremity infiltration, with extension into the perineum.
Fig. 6: Venous malformation of the knee with intra-articular and osseous involvement; patient at risk for hemosiderin arthropathy.
On T2WI, these lesions are markedly hyperintense, though focal low signal areas may be seen corresponding to areas of hemorrhage or phleboliths; they are nearly isointense to skeletal muscle on T1WI. Time-resolved imaging reveals no significant arterial inflow (low-flow anomaly), with progressive patchy enhancement beginning during the venous phase of enhancement, and continually increasing over time. Delayed post-contrast imaging demonstrates central enhancement, as opposed to the strictly septal enhancement seen in lymphatic malformations (Fig. 5–7).
Fig. 7: Venous malformation. Dusky mass posterior to achilles tendon (a). Isointense on T1WI (b) and hyperintense on T2WI (c) to muscle; note phleboliths (yellow arrows). Time-resolved CE MRA demonstrates no high-flow component and normal three-vessel runoff to foot (d) with delayed, progressive lesion enhancement (arrows: e,f).
Lymphatic Malformations
Lymphatic malformations, like all other vascular malformations, are present at birth. While these lesions grow commensurately with the child, they can become acutely enlarged secondary to hemorrhage or infection. Again like all other malformations, they can present as localized or diffuse masses. When superficially located, vesicles representing extension of the deeper lymphatic malformation may be seen on the skin surface. Hemihypertrophy and extremity enlargement is most often seen with lymphatic malformations, in part because of lymphatic congestive changes. Pathologically, they are composed of abnormal sponge-like collections of dilated lymphatic channels/spaces.
Fig. 8: Lymphatic malformation. Large rubbery left neck/facial mass (a). T1WI (b) and T2WI (c) images demonstrate cystic mass with areas of hemorrhage (arrow). Axial CE FS T1 GRE image reveals septal enhancement.
Fig. 9: Lymphatic malformation. Left axillary cystic mass with areas of high signal hemorrhage on T1WI (a) and septal enhancement on CE T1 FS GRE (b) and T2W FS coronal (c).
MR imaging will vary depending upon the size of the cysts (macro vs. microcystic). In a pure macrocystic lymphatic malformation, delayed contrast imaging will reveal septal enhancement, with a total lack of central (intracystic) enhancement (Fig. 8, 9). Microcystic lymphatic malformations can be difficult to differentiate from venous malformations, as mixed venolymphatic malformations often occur. Of note, the term “lymphatic malformation” is preferred to the terms “lymphangioma” and “cystic hygroma,” as the suffix incorrectly suggests the presence of a proliferative lesion.
Fig. 10: Myofibroblastic tumor. Axial T2 FS WI (a), Coronal time-resolved MRA (b), and Axial CE T1 FS GRE (c) show infiltrative heterogeneous signal intensity and contrast enhancement. Clinically, this was a hard palpable mass.
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