Immunohistochemically, the perivascular epithelioid cells show positivity for melanocytic markers, such as HMB-45 and Melan-A, as well as smooth muscle markers, such as actin and myosin.1 Here, we report the first case of a malignant PEComa arising in the gallbladder.
REPORT OF A CASEThe patient was a 46-year-old woman who was diagnosed with high-grade invasive ductal carcinoma of the left breast showing left sentinel node metastasis in 2010. Both estrogen and progesterone receptor status were negative by immunohistochemistry. She received 4 cycles of preoperative chemotherapy, followed by left mastectomy and left axillary lymph node dissection. She then received adjuvant chemotherapy, as well as regional radiotherapy. In September 2012, the patient presented with right upper quadrant pain. An ultrasound of the abdomen suggested a primary gallbladder wall malignancy with regional nodal metastasis and possible hepatic invasion. A computed tomography scan of the abdomen and pelvis revealed a gallbladder mass extending into the pericholecystic fat and inseparable from the liver, with an enlarged portacaval lymph node measuring up to 3.3 cm with mild compression of the inferior vena cava (Figure 1, A). A computed tomography scan of the chest showed no evidence of distant metastatic disease. She subsequently underwent an open cholecystectomy in October 2012.
Macroscopic ExaminationThe cholecystectomy specimen weighed 62.2 g and consisted of a previously opened gallbladder resected en bloc with its underlying 6.5 3 4.0 3 2.5-cm liver bed. The fixed gallbladder measured up to 11.0 cm. There was a large tumor mass within the lumen of the gallbladder that measured 5.5 3 4.5 3 3.3 cm (Figure 1, B). The tumor was arising in the fundic portion of the gallbladder and grossly did not extend closer than 4.0 cm from the cystic duct resection margin. The tumor invaded the wall of the gallbladder. Aside from this large tumor the gallbladder mucosa was otherwise normal. No calculi were identified.
Microscopic ExaminationThe tumor infiltrated through the full thickness of the gallbladder wall. It abutted the serosa, but the tumor cells were separated from the serosal surface by a thin strand of connective tissue. The neoplastic cells were epithelioid and characterized by clear to granular, lightly eosinophilic cytoplasm and small, centrally located, normochromatic, round to oval nuclei (Figure 2, A and B). The nuclei showed slight variation, and most demonstrated small nucleoli. The cells had fairly distinct cell borders and were arranged as nests and sheets. Scattered mitotic figures were noted. There was no evidence of necrosis or hemorrhage. Clearly defined lymphovascular space invasion was present. Aside from the fundic tumor, the remaining gallbladder mucosa, including cystic duct sections, was benign. There were small nodules of tumor in the liver with similar morphology, underlying the gallbladder, which did not involve the resected margin of the liver. Contiguous spread between the liver tumor and the gallbladder tumor was...