Clinical Pearls & Morning Reports
Published December 19, 2018
The presence of antineutrophil cytoplasmic antibodies (ANCA) supports the diagnosis of granulomatosis with polyangiitis; however, these antibodies are detected in only 20% of cases in which involvement is confined to the orbit. Read the Latest NEJM Case Records of the Massachusetts General Hospital here.
Q: Which extraocular muscle is most often involved in thyroid eye disease?
A: The characteristic orbital feature of thyroid eye disease is enlargement of the extraocular muscles with sparing of the tendinous insertion to the globe. The enlargement of extraocular muscles tends to occur in a typical anatomical pattern; the inferior rectus muscle is most commonly affected, followed by the medial and superior rectus muscles, and the lateral rectus muscle is least commonly affected.
Q: How often is the orbit involved in IgG4-related disease?
A: Approximately one quarter of cases of IgG4-related disease involve the orbit. Tissues that may be involved include the lacrimal gland, orbital fat, extraocular muscles, and cranial or orbital nerves, such as the infraorbital nerve.
A: The generalized form of granulomatosis with polyangiitis affects vascular, respiratory, and renal tissues, whereas the limited form is restricted to the upper respiratory tract, the paranasal sinuses, and by extension, the orbits. Orbital involvement is common in both forms, occurring in approximately 50% of cases. Orbital manifestations include an extraconal mass adjacent to an affected paranasal sinus, as well as diffuse orbital and lacrimal-gland inflammation.
A: Granulomatosis with polyangiitis has long been known to be a disease for which two medications, not glucocorticoids alone, are needed to induce remission. For 40 years, the standard of care for remission induction in granulomatosis with polyangiitis was the combination of cyclophosphamide and glucocorticoids. In 2010, this standard of care was challenged and overturned on the basis of the results of the Rituximab in ANCA-Associated Vasculitis (RAVE) trial, a head-to-head comparison of rituximab with cyclophosphamide for remission induction. Rituximab was noninferior to cyclophosphamide among all the patients in the trial and was superior among patients who had ANCA directed against proteinase 3; however, 24% of the patients in the trial (21% of those who received rituximab and 27% of those who received cyclophosphamide) had persistent or recurrent active disease during the first 6 months.