Lu Z, et al. - Given that renomedullary interstitial cell tumors (RMICT) are usually recognized either at autopsy or resection of the kidney for other reasons, researchers analyzed the immunohistochemical phenotype of usual, incidental RMICT using modern soft tissue tumor markers. For this investigation, they recovered 41 RMICTs from 36 subjects and analyzed pathologic features including morphology, immunohistochemistry (S100, keratin AE1/AE3, smooth muscle actin, desmin, estrogen and progesterone receptors, calponin, CD34, CD35), and histochemical staining. Results of this study suggested that weak staining could be seen for muscle markers and hormone receptors (estrogen and progesterone). Data reported that CD34 was usually negative, with occasional weak labeling, in contrast to solitary fibrous tumor.