Ovarian
steroid cell
tumors, not otherwise specified (SCTs, NOS) are uncommon
sex cord-stromal tumors that may be difficult to distinguish from other oxyphilic or clear-cell
neoplasms. Immunohistochemical staining for
inhibin, although generally useful in the diagnosis of SCTs, NOS, is not positive in every case and not all laboratories have this marker available. Recently, it has been reported that
calretinin is expressed by
sex cord-stromal tumors. We studied six SCTs, NOS for both
calretinin and
inhibin expression to evaluate the sensitivity of
calretinin in comparison to
inhibin. We also tested for CD99,
Melan-A (A103), and S-100, other markers reported to be positive in these
tumors. HMB-45 and MART-1 (Ab3) completed our panel of markers. All six
tumors were positive for both
calretinin and
inhibin.
Calretinin positivity was present in 60% to >90% of
tumor cells, whereas
inhibin reactivity ranged from <5% to >90% of
tumor cells. Membranous staining for CD99 was present in one
tumor. S-100-positive cells were seen in two
tumors, whereas four
tumors were immunoreactive for HMB-45. All six
tumors were positive for
Melan-A (A103), but in general the staining was less diffuse than with
calretinin. All of the
tumors were essentially negative for MART-1 (Ab3). The consistent diffuse staining of the
tumors in this study for
calretinin, in comparison to
inhibin and
Melan-A (A103), suggests that it is a sensitive marker for SCTs, NOS. MART-1 (Ab3) immunostaining may be useful for cases in which
melanoma is considered in the differential diagnosis.