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Perivascular epithelioid cell tumors (PEComas) are a family of mesenchymal neoplasms that have smooth muscle and melanocytic differentiation. They can be sporadic or associated with tuberous sclerosis complex and commonly present in the kidney as angiomyolipoma or in the lung as pulmonary clear cell sugar tumors or lymphangioleiomyomatosis. However, they can present at any visceral or soft tissue site. They usually have a benign clinical course, but rarely can behave in a malignant fashion. Most PEComas demonstrate abnormalities of TSC2, but a recently described subset harbor TFE3 rearrangements that seem to be mutually exclusive of TSC2 alterations. TFE3-rearranged PEComas demonstrate a distinct alveolar morphology that lacks spindle cells and smooth muscle differentiation. Distinction between these may have important therapeutic consequences. Herein, we present a case of a TFE3-rearranged PEComa without the customary morphology that required ancillary investigation with TFE3 immunohistochemistry and break-apart fluorescence in situ hybridization for proper categorization.

Цель работы – определение степени злокачественности и прогноза заболевания у больных с «сахарной» опухолью легкого.Материалы и методы. Описан и проанализирован случай светлоклеточной («сахарной») опухоли легкого у больной 76 лет.Результаты. Размеры и скорость роста узловых образований в легких имеют высокую корреляцию с вероятностью их злокачественности. Доброкачественные образования имеют или очень малое (менее 1 месяца при воспалительных процессах), или очень большое (более 16 месяцев) время удвоения опухолевой массы. Отсутствие роста солидного (плотного) узла в течение 2–3 лет – надежный критерий его доброкачественности. Время удвоения опухолевой массы злокачественных опухолей обычно составляет от 40 до 360 дней. Время удвоения опухолевой массы у данной больной – 379 дней.Выводы. Светлоклеточная, или «сахарная» опухоль скорее является высокодифференцированной злокачественной опухолью с достаточно длительным временем удвоения опухолевой массы, чем доброкачественной. Косвенно на это указывает низкий уровень пролиферативной активности опухоли, коэкспрессия виментина., Aim. Determination of the degree of malignancy and prognosis of the disease in patients with a “sugar” lung tumor.Material and methods. The case of a light-cell (“sugar”) lung tumor in a 76-year-old patient is described and analyzed.Results. The size and rate of growth of nodal formations in the lungs have a high correlation with the probability of their malignancy. The benign formations are either very small (less than 1 month in inflammatory processes), or very large (more than 16 months) time duplication of tumor mass. Lack of growth of a solid (dense) node within 2–3 years is a reliable criterion for its benign quality. The time to double the tumor mass of malignant tumors is usually in the range of 40 to 360 days. The time to double the tumor mass in this patient is 379 days.Conclusion. The light-cell or “sugar” tumor is more likely to be a highly differentiated malignant tumor with a fairly prolonged time doubling of tumor mass than benign tumor. The low level of proliferative activity of the tumor, coexpress of vimentinum also indicates this., Мета роботи – визначення ступеня злоякісності та прогнозу захворювання у хворих на «цукрову» пухлину легені.Матеріали та методи. Описано та проаналізовано випадок світлоклітинної («цукрової») пухлини легені у хворої 76 років.Результати. Розміри та швидкість зростання вузлових утворень у легенях мають високу кореляцію з імовірністю їх злоякісності. Доброякісні утворення мають або дуже малий (менше ніж 1 місяць при запальних процесах), або дуже великий (понад 16 місяців) час подвоєння пухлинної маси. Відсутність зростання солідного (щільного) вузла протягом 2–3 років є надійним критерієм його доброякісності. Час подвоєння пухлинної маси злоякісних пухлин зазвичай становить від 40 до 360 днів. Час подвоєння пухлинної маси в цієї хворої дорівнює 379 днів.Висновки. Світлоклітинна, або «цукрова» пухлина радше є високодиференційованою злоякісною пухлиною з доволі тривалим часом подвоєння пухлинної маси, ніж доброякісною. Опосередковано на це вказує низький рівень проліферативної активності пухлини, коекспресія віментину.

Perivascular epithelioid cell tumors (PEComas) are rare neoplasms that share phenotypic features with angiomyolipomas, clear cell sugar tumors, and lymphangioleiomyomatosis. They presumably represent the neoplastic counterpart of a yet-unidentified perivascular epithelioid cell that expresses smooth muscle and melanocytic immunomarkers. The uterus is the second most common site of origin for perivascular epithelioid cell tumors, after the retroperitoneum. Although most uterine perivascular epithelioid cell tumors are clinically benign and can be cured by a complete surgical excision, there is a subset characterized by both local and distant dissemination. Unfortunately, no single histopathologic or immunohistochemical parameter can accurately predict the clinical behavior of these tumors, which is why the 2012 World Health Organization classification of tumors of the female reproductive organs suggests the use of several criteria to predict the risk of aggressive clinical behavior. Here we review those perivascular epithelioid cell tumors of the uterine corpus with aggressive clinical behavior reported in the literature, and we discuss their most relevant clinical and histopathologic features.

Neoplasms of the perivascular epithelioid cell (PEComas) represent a recently described heterogeneous group of mesenchymal tumors characterized by the presence of specific histological, immunohistochemical, and ultrastructural findings. The PEComas encompass a family of neoplasms that include angiomyolipomas, clear cell sugar tumors, and lymphangioleiomyomatosis. The PEComas demonstrate a wide spectrum of clinicobiological behavior and imaging findings. Perivascular epithelioid cell, as the name implies, is a unique cell that is characterized by perivascular distribution and epithelioid morphology. Perivascular epithelioid cell consistently shows immunoreactivity to melanocytic and smooth muscle markers including HMB-45 and actin. Abdominopelvic PEComas are found at a variety of somatic and visceral locations including kidney, liver, pancreas, gastrointestinal tract, genitourinary tract, peritoneum, and retroperitoneum. A subset of patients with abdominopelvic PEComas manifests tuberous sclerosis complex. In this paper, we review the histological spectrum and discuss the imaging findings of the PEComas that involve the abdomen and pelvis.

Neoplasms of perivascular epithelioid cells (PEComas) have in common the coexpression of muscle and melanocytic immunohistochemical markers. Although this group includes entities with distinct clinical features, such as angiomyolipoma, clear cell sugar tumor of the lung, and lymphangioleiomyomatosis, similar tumors have been documented in an increasing diversity of locations. The term PEComa is now generally used in reference to these lesions that are not angiomyolipomas, clear cell sugar tumors, or lymphangioleiomyomatoses. While most reported PEComas have behaved in a benign fashion, malignant PEComas have occasionally been documented. We present a case of hepatic PEComa with benign histologic features, which nonetheless presented with metastases to multiple sites nearly 9 years later. This case represents the second documented malignant PEComa of the liver, as well as the longest follow-up of a surviving patient with a malignant PEComa, emphasizing both the need for criteria that more accurately predict the behavior of PEComas and the necessity of long-term follow-up of patients with PEComas.

HMB-45-positive clear-cell epithelioid tumor arising in the ligamentum teres hepatis of a 13-year-old Japanese girl is described. The well-defined tumor was completely removed and measured 9 x 7 x 6 cm. Cut sections showed a tan-white, homogeneous appearances with no hemorrhage or necrosis. The tumor was composed of nests or sheets of polygonal or oval-shaped cells rich in clear or finely granular cytoplasm. Capillary network was well developed, and sinusoid vessels were often seen with occasional perivascular hyalinization. There was moderate nuclear atypia but mitotic figures were absent. Periodic acid-Schiff stain showed a large amount of glycogen digested by diastase. Immunohistochemical stains for smooth muscle actin, Melan-A, and HMB-45 were positive in most of the tumor cells. Stains for vimentin, muscle actin, and HAM56 were focally positive, whereas stains for desmin, cytokeratin, epithelial membrane antigen, S-100, CD34, CD68, CD99, neurofilament proteins, and estrogen/progesterone receptors were negative. Ultrastructurally, the cytoplasm contained a considerable number of mitochondria, monoparticipate or membrane-bound glycogen, and longitudinally oriented thin filaments with focal condensations and subplasmalemmal densities. The histopathology of the present case, originally interpreted as epithelioid leiomyoma, was consistent with clear cell "sugar" tumors. The present case may indicate ubiquitous distribution of clear cell "sugar tumors" of which histogenesis remains unknown but is presumed to be of perivascular epithelioid cell origin.

In recent years, a group of tumors that have been designated "perivascular epithelioid cell tumors" (PEComa) have been reported with increasing frequency from a wide variety of anatomic locations. The uterus and retroperitoneum appear to be the most frequent sites of origin for these lesions. PEComas belong to an identically named family of tumors comprised of conventional angiomyolipomas, clear cell sugar tumors, lymphangiomyomatosis and clear cell myomelanocytic tumor of the falciform ligament/ligament teres, and are also known as PEComa-NOS. This article is a primer for clinicians on the most salient clinicopathologic features of uterine PEComas, as most of the debate and discussion have taken place in the pathologic literature. The author appraises in detail the current state of knowledge on PEComas of the uterus based on a review of published data on the 44 previously reported cases, and comments on areas of controversy. The latter are centered predominantly on the significant morphologic and immunophenotypic overlap that exists between uterine PEComa and some smooth muscle tumors of the uterus. The clinicopathologic features of cases reported as epithelioid smooth muscle tumors and cases reported as uterine PEComas are compared and contrasted, and a practical approach to their reporting is proposed.

Clear cell "sugar" tumor is a rare benign tumor considered as a member of the family of perivascular epithelioid cell tumors. To the best of our knowledge, this is the first case of clear cell "sugar" tumor presented as a mass protruding from the urethra in a 15-year-old girl. Pathologic examination revealed a tumor composed of epithelioid cells with "water" clear cytoplasm that stained positively for melanocytic and smooth muscle-specific markers. Treatment of this tumor included a surgical excision and complete removal of the urethral mass, with examination of surgical margins. Three months after surgery, the patient remains clinically free of disease.