Abstract
BackgroundPerivascular epithelioid cell tumor (PEComa), other than angiomyolipoma (AML), clear cell sugar tumor (CCST), and lymphangioleiomyomatosis (LAM), is a very rare mesenchymal tumor with an unpredictable natural history. The uterus is the most prevalent reported site of involvement of PEComa-not otherwise specified (PEComa-NOS). To the best of our knowledge, about 100 PEComa-NOS have been reported in the English Language medical literature, of which 38 were uterine PEComa-NOS. These reported cases of uterine PEComa-NOS have usually shown clinically benign behavior, but 13 tumors, three of them associated with tuberous sclerosis complex (TSC), exhibited local aggressive behavior and four of them showed distant metastases.Case presentationWe report the case of a 59-year-old woman, who presented with renal and pulmonary lesions seven years after the initial diagnosis of uterine leiomyosarcoma. Left nephrectomy and right middle lobe wedge resection were performed. Histological and immunohistochemical analysis of the renal and pulmonary lesions, in addition to retrospective re-evaluation of the previous uterine tumor, led to the final diagnosis of malignant uterine PEComa with late renal and pulmonary metastases. All three lesions had the typical histological appearance of PEComa-NOS showing a biphasic growth pattern with continuous transition between spindle cells and epithelioid cells, often arranged around vascular spaces. Immunohistochemically, the tumor cells of both phenotypes in all three lesions stained for melanocytic (HMB-45 and Melan-A/MART-1) and myoid (desmin, smooth muscle actin, and muscle-specific actin/all muscle actin/HHF-35) markers.ConclusionThe findings indicate that despite the small number of reported cases, PEComas-NOS should be considered tumors of uncertain malignant potential, and metastases to other organs might become evident even several years after the primary diagnosis.
Highlights
Perivascular epithelioid cell tumor (PEComa), other than angiomyolipoma (AML), clear cell sugar tumor (CCST), and lymphangioleiomyomatosis (LAM), is a very rare mesenchymal tumor with an unpredictable natural history
Bonetti and colleagues [3] proposed a cellular link between AML, CCST, and lymphangioleiomyomatosis (LAM), their association with tuberous sclerosis complex (TSC), and advanced the concept of a family of neoplasms composed of this distinctive cell which was "immunoreactive with melanocytic markers, and exhibit an epithelioid appearance, a clear-acidophilic cytoplasm, and a perivascular distribution"
We report the case of a 59-year-old woman who presented with renal and pulmonary lesions seven years after the initial diagnosis of uterine leiomyosarcoma, but histological and immunohistochemical analysis of the renal, pulmonary and previous uterine lesions led to the final diagnosis of malignant uterine PEComa-NOS with late renal and pulmonary metastases
Summary
We have described a case of malignant PEComa-NOS of the uterus with late renal and pulmonary metastases seven years after hysterectomy. PEComas-NOS show a marked female predominance, are rare but anatomically ubiquitous mesenchymal tumors that are composed of nests and sheets of usually epithelioid but occasionally spindled cells with clear to granular eosinophilic cytoplasm and a focal association with vascular spaces. They usually show immunoreactivity for both melanocytic (HMB-45 and/or Melan-A/Mart-1) and myoid/musclespecific (actin and/or desmin) markers, which are useful for confirming the diagnosis. AML, angiomyolipoma; CCMMT, clear cell myomelanocytic tumour; CCST, clear cell sugar tumour; LAM, lymphangiomyomatosis; PEC, perivascular epithelioid cell; PEComa, perivascular epithelioid cell tumor; TSC, tuberous sclerosis complex
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