Cutaneous Granular Cell Tumor of the Breast J Clin Med Res • 2010;2(4):185-188 pattern at the margins. The granules were PAS-positive and diastase-resistant in varying degrees of intensity. The immu- nohistochemical study showed that tumor cells were posi- tive for S100 protein, vimentin, inhibin, and CD68 and were negative for cytokeratin AE1/AE3, smooth muscle actin, desmin, and estrogen and progesterone receptors (Fig. 3). Ki-67 revealed low nuclear proliferative activity. The tumor was completely excised. No evidence of tumor recurrence in left breast has been detected after four-years of follow-up. Discussion Granular cell tumor was first described by Abrikossoft in 1926. It was originally designated myoblastoma [2] and con- sidered to derive from smooth muscle, due to its localization in tongue and pharynx in the first reported cases. Subsequent studies using S100 staining and electron microscopy found that the tumor cells originate in Schwamm cells of peripheral nerves [3, 4] and can appear at any site (skin, lymph nodes, appendix, etc.). The most frequent localizations are the head and neck (> 50% of cases) and the tongue (≈ 40% of cases). GCT of the breast is very uncommon, representing around 1/1,000 cases of breast cancer [1]. Analysis of data from the 25 cases reported in the literature and the present case (22 females and 3 males) revealed that premenopausal women were the most frequently affected, with a mean age at onset of 40.3 years (range: 17 - 83 years). We have found no report of GCT of breast in a woman as old as our 83-year-old patient. [1, 5-12]. The low reported incidence in males may be ex- plained by their much less frequent participation in regular mammography screening. This tumor is most frequently ob- served in upper inner quadrant, whereas it was localized in the lower inner quadrant in our patient. On radiographic or ultrasound images, GCT appears as a well-defined mass or as an infiltrating spiculated lesion, with no microcalcifications described in the majority of reports [6-12]. In the present case, it appeared as a poorly-defined infiltrating mass with clinical suspicion of malignity, as re- ported in 29% of the 24 cases reviewed. The two reports of magnetic resonance images of GCT are controversial. One describes a homogenously enhanced mass on T1-weighted imaging with high signal intensity rim on T2-weighted sequence, and a high T2-signal has been shown to be a sign of benign disease [13]. The other describes a homogeneously enhanced mass with no true pe- ripheral rim or peripheral predominance of T1 signal, which showed a very low signal on T2-weighted imaging, which is more frequently observed in malignant than benign lesions of the breast [14]. Microscopically, CGT is characterized by rounded, po- lygonal, and occasionally elongated cells with a wide and granular cytoplasm; the nuclei can be small and hyperchro- matic or larger and vesicular. A similar morphology can be observed in smooth muscle tumors, malignant melanoma, angiosarcoma, and even breast carcinomas [15]. The diag- nosis of CGT can be established by immunohistochemistry or by the demonstration of electrodense granular structures corresponding to secondary lisosomes. Less than 1% of CGTs are malignant. The histopatho- logic criteria for malignity are: tumor more than 5 cm, pres- ence of necrosis, high mitotic activity, and nuclear pleomor- phism. These criteria were not met in the present case. We highlight the association of CGT with infiltrating ductal carcinoma, which has been described in three patients of advanced age [16]. Usually CGT is treated by wide local excision to avoid local recurrences. The message of the present report is that CGT of the breast should be included in the clinical differential diagno- sis with carcinoma, especially in elderly patients with risk factors. Conflict of Interest The authors have no conflict of interest to declare. References 1. Adeniran A, Al-Ahmadie H, Mahoney MC, Robinson- Smith TM. Granular cell tumor of the breast: a se- ries of 17 cases and review of the literature. Breast J 2004;10(6):528-531. 2. Abrikosoff A. Weitere untersuchungen uber mublasten- myome. Virchow Arch Path Anat 1931; 280:723. 3. Dhillon AP, Rode J. Immunohistochemical studies of S100 protein and other neural characteristics ex- pressed by granular cell tumour. Diagn Histopathol 1983;6(1):23-28. 4. Lifshitz MS, Flotte TJ, Greco MA. Congenital granu- lar cell epulis. Immunohistochemical and ultrastructural observations. Cancer 1984;53(9):1845-1848. 5. Gordon AB, Fisher C, Palmer B, Greening WP. Granular cell tumour of the breast. Eur J Surg Oncol 1985;11(3):269-273. 6. Patel A, Lefemine V, Yousuf SM, Abou-Samra W. Gran- ular cell tumour of the pectoral muscle mimicking breast cancer. Cases J 2008;1(1):142. 7. Pojchamarnwiputh S, Muttarak M, Na-Chiangmai W, Chaiwun B. Benign breast lesions mimicking carcinoma at mammography. Singapore Med J 2007;48(10):958- 968. 8. Leo C, Briest S, Pilch H, Schutz A, Horn LC, Leinung S. Granular cell tumor of the breast mimicking breast can- cer. Eur J Obstet Gynecol Reprod Biol 2006;127(2):268- 270. Articles © The authors | Journal compilation © J Clin Med Res and Elmer Press™ | www.jocmr.org 187