Histopathology and immunohistochemistry of peripheral neural sheath tumor and perivascular wall tumor in dog / Histopatologia e imuno-histoquímica de tumor de bainha de nervo periférico e de tumor de parede perivascular em cães

Soft tissue sarcomas (STS) comprise a heterogeneous group of malignancies derived from extra-skeletal mesenchymal tissues that may show similar histopathological changes. Histopathologic patterns suggestive of perivascular wall tumors (PWT) and peripheral nerve sheath tumors (PNST) have been described. This study investigated the histogenesis in a series of 71 cases of canine STS that showed morphological compatibility with what is described for PWT and PNST. Immunohistochemistry analysis were done to CD56, S100, SMA, Desmin, Von Willebrand Factor, NSE and GFAP. Twenty-one cases (29.6%) showed histopathologic features compatible with PWT, 23 cases (32.4%) with PNST and 27 cases (38.0%) shared both histopathological features. By immunohistochemistry, 59 (83.1%) cases showed positivity only for neural markers and 12 (16.9%) had simultaneous positivity for both neural and muscle markers. PNST was the most prevalent neoplasm and none of the cases were positive for muscle markers only. The histopathologic features were not useful to define the diagnosis of PWT, since most tumors were negative for muscle markers but positive for neural markers. Due to this immunoreactivity and the morphologic features, future studies may propose guidelines for the classification of these neoplasms.(AU)

Sarcoma de tecidos moles (STM) compreende um grupo heterogêneo de neoplasias malignas, derivadas de tecidos extraesqueléticos, que podem apresentar alterações histopatológicas similares. Os padrões histopatológicos sugestivos de tumor de parede perivascular (TPP) e de tumor de bainha de nervo periférico (TBNP) têm sido descritos. Este estudo investigou a histogênese de uma série de 71 STM caninos, que apresentavam compatibilidade morfológica com o que é descrito para TPP e TBNP. A análise imuno-histoquímica foi feita para CD56, S100, SMA, Desmina, Fator Von Willebrand, NSE e GFAP. Vinte e um casos (29,6%) apresentaram características histopatológicas compatíveis com TPP, 23 casos (32,4%) com TBNP e 27 casos (38,0%) apresentaram características histopatológicas de ambos. Na imuno-histoquímica, 59 (83,1%) casos apresentaram positividade somente para marcadores neurais e 12 (16,9%) tiveram positividade simultânea tanto para marcadores neurais como para marcadores musculares. TBNP foi a neoplasia mais prevalente e nenhum dos casos foi positivo para somente para marcadores musculares. As características histopatológicas não foram úteis para definir o diagnóstico de TPP, uma vez que a maioria foi negativa para marcadores musculares, mas positiva para marcadores neurais. Devido a essa imunorreatividade e às características morfológicas, pesquisas futuras poderão propor orientações para a classificação dessas neoplasias.(AU)

PEComa (neoplasia de células epiteliodes perivasculares) asociado con cáncer papilar de tiroides bilateral sincrónico / PEComa (Perivascular Epithelioid Cell Neoplasms) associated with synchronous bilateral papillary thyroid cancer

Resumen Introducción: Los tumores de células epitelioides perivasculares (PEComas) son neoplasias poco frecuentes de origen mesenquimal. Estos incluyen el angiomiolipoma epitelioide (EAML), una neoplasia con potencial maligno y cuya presentación simultánea con cáncer de tiroides es bastante rara. Presentación del caso: Hombre de 40 años con masa de crecimiento rápido en relación con polo inferior derecho de tiroides e infiltración de tráquea. La TAC abdominopélvica contrastada muestra múltiples masas renales con masa dominante en polo superior izquierdo. El estudio histopatológico de tiroides evidenció una lesión en lóbulo derecho correspondiente a cáncer papilar de tiroides (PTC) de variante de células altas y una segunda neoplasia en el lóbulo contralateral correspondiente a PTC moderadamente diferenciado de variante clásica. En riñón se encontró una lesión correspondiente a EAML, con células de aspecto epitelioide equivalentes al 40%. Discusión: El presente artículo corresponde al primero en la literatura en describir la presentación simultánea de EAML con PTC bilateral sincrónico (SBiPTC). Se describe una vía molecular común, que corresponde a la vía TSC/mTOR, la prevalencia de SBiPTC y los marcadores inmunohistoquímicos para diagnóstico de EAML.

Abstract Introduction: Perivascular Epithelioid Cell Neoplasms (PEComas) are uncommon tumors of mesenchymal origin. These ones include the epithelioid angiomyolipoma (EAML), a tumor with malignant potential and whose simultaneous presentation with thyroid cancer is quite rare. Presentation of case: Forty years old man with fast-growing mass in relation to lower right thyroid pole and tracheal infiltration. Abdominopelvic contrast-enhanced CT shows multiple renal masses with dominant mass in the left upper pole. Thyroid histopathology showed a lesion in right lobe corresponding to tall cell variant of papillary thyroid cancer (PTC) and a second neoplasm in the contralateral lobe corresponding to classical variant of moderately differentiated PTC. In the kidney was found a tumor corresponding to EAML with epithelioid aspect cells equivalent to 40%. Discussion: This article corresponds to the first in the literature to describe the simultaneous presentation of EAML with synchronous bilateral PTC (SBiPTC) and its possible association. A common molecular pathway corresponding to the TSC/mTOR pathway is described, as well as SBiPTC prevalence and immunohistochemical markers for EAML diagnosis.

Angiomiolipoma renal: ¿es siempre un tumor benigno? / Renal angiomyolipoma: Is it always a benign tumor?

El angiomiolipoma (AML) renal es un tumor sólido compuesto por células de músculo liso, vasos sanguíneos dismórfi cos y tejido adiposo. Esta lesión ha sido considerada siempre como una neoplasia benigna. Reportamos a una paciente de 44 años, asintomática, con una lesión sugerente de AML mayor a 4 cm en el TAC que fue sometida a nefrectomía parcial abierta. La biopsia definitiva informó un angiomiolipoma con componente epiteloídeo focal (AMLE). Controles de imágenes posteriores de esta paciente no han evidenciado recidivia. El angiomiolipoma epiteloídeo (AMLE) es una variante descrita en los últimos años y que sugiere un cambio en el paradigma clásico de “benignidad” asociada al AML Las guías para el manejo de los AML no toman en cuenta la posibilidad de que se trate de un AMLE en sus recomendaciones. Existe muy poca información respecto al manejo de este tipo de lesiones, sólo hay series de casos publicadas. Faltan estudios prospectivos que otorguen herramientas para la toma de decisiones terapéuticas adecuadas en estos pacientes.

Renal angiomyolipoma (AML) is a solid tumor formed by smooth muscle cells, dimorphic blood vessels and adipose tissue. This lesion has been always considered as a benign neoplasm. We report an asymptomatic 44 year-old female patient, with a tumor suggesting an AML in a CT scan greater than 4 cms, who had an open partial nephrectomy. The biopsy report showed an AML with a focal epithelioid component. Follow-up imaging in this case has not showed any recurrence. Epithelioid angiomyolipoma (EAML) is a variant with malignant potential that must be considered when a patient with a renal AML is been evaluated. Guidelines for AML management do not take AMLE as a differential diagnosis. Few studies have been published regarding the management of this kind of lesion, only consisting of case series. There is lack of prospective studies that could give tools for the decision-making process in the treatment of these patients.

Retroperitoneal sclerosing PEComa with melanin pigmentation and granulomatous inflammation-A rare association within an uncommon tumor.

PEComa, defined as a perivascular epithelioid cell tumor, displays a wide clinicopathological spectrum. Lately, a sclerosing PEComa has been identified as its distinct variant, but with limited documentation, in view of its rarity. Herein, we describe an uncommon case of a 53-year-old lady, who was referred to us with pain abdomen. Radiological imaging disclosed a well-defined, hypodense retroperitoneal mass. The excised tumor was a round, encapsulated soft tissue mass measuring 7 cm with a tan-brown cut surface. Microscopy showed uniform, epithelioid cells with clear cytoplasm, focal melanin pigmentation and mild nuclear atypia, arranged in sheets and nests around capillary-sized vessels in a dense sclerotic stroma. Additionally, co-existing epithelioid granulomas were noted. On immunohistochemistry (IHC), tumor cells were diffusely positive for HMB45; focally for desmin and smooth muscle actin (SMA), while negative for EMA, CD10, S100-P, Melan A, CD34, AMACR and CK MNF116. This case reinforces sclerosing PEComa as an uncommon, but a distinct clinicopathological entity and exemplifies diagnostic challenge associated with it; necessitating application of IHC markers for its correct identification. Presence of melanin pigment and granulomatous inflammation in the present tumor constitute as novel histopathological findings in a sclerosing PEComa.

Perivascular epithelioid cell tumor [PEComa] of the uterus with aggressive behavior at presentation

Perivascular epithelioid cell tumor [PEComa] is a rare mesenchymal tumor composed of histologically and immunohistochemically distinctive perivascular epithelioid cells [PECs]. Both benign and malignant tumors have been identified, but the criteria for diagnosis of malignancy have not been fully established due to the rarity of the tumor. We report on a case of uterine PEComa in a 33-year old woman with lymph node metastasis at presentation. The tumor had the characteristic histologic features of PEComa with cytologic atypia, mitotic activity of 2/10 high power field [HPF], and necrosis; it exhibited immunopositivity for HMB-45, calponin and desmin and was negative for melan-A. The patient received neoadjuvant chemotherapy, debulking surgery and adjuvant chemotherapy. No evidence of recurrence or metastasis was apparent 8 months after surgery