Letter to the Editor

Myopericytoma of the parotid gland – A pathological conundrum

Presentamos el caso de una mujer de 21 años sin antecedentes de interés, que presentó dolor abdominal y masa perceptible en hipocondrio izquierdo. La tomografía axial computarizada informó de imagen tumoral de 7 cm de diámetro, en la porción media y cara anterior del riñón izquierdo. Se le realizó nefrectomía total izquierda. El examen histológico reveló proliferación de células ovoides con distribución concéntrica perivascular e imagen glomangiopericitoide, inmunoreactividad para actina de músculo liso, y miosina de músculo liso y ausencia de reactividad para la desmina, con diagnóstico concluyente de miopericitoma renal. Este es un tumor infrecuente de células mioides perivasculares, considerado por la mayoría como una neoplasia de piel y partes blandas con escasos reportes de presentaciones en vísceras. Hasta el momento 4 casos de miopericitoma renal se han reportado en la literatura médica. Reportamos otro nuevo caso de esta inusual ubicación.

Myopericytoma is an infrequent neoplasm of perivascular myoid cells that usually originates in the skin and superficial soft tissues of distal extremities but is rarely found in the visceral organs. Only four cases of renal myopericytoma have been previously reported. We present a further case of myopericytoma of the kidney in a 21 year old woman with no clinical history of interest who presented with abdominal pain and a palpable mass in the left upper quadrant. Unenhanced computed tomography revealed a 7 cm diameter mass in the middle portion and anterior aspect of the left kidney. The patient underwent left radical nephrectomy. Histological examination revealed a tumour composed of ovoid cells in a concentric arrangement and a «glomangiopericytoma» pattern. Immunohistochemistry showed positivity for smooth muscle actin, and smooth muscle myosin stains and negativity for desmin, confirming the diagnosis of renal myopericytoma.

The purpose of this study was to explore any association between anatomical variances in the ductal system and sialolith formation using sialoendoscopy and acrylic resin replication of the ductal system.

A retrospective study of 372 submandibular gland sialoendoscopies was performed to review the findings of the submandibular gland duct anatomy. Using sialoendoscopy and replicated casts, a high rate of hilar widening was noted in patients with submandibular sialolithiasis.

Sialolithiasis was detected in 326 of the patients who presented with obstructive symptoms. Around 67% (285/426) of the stones were located in the distal third of the ducts or at the hilum of the submandibular gland. During the sialoendoscopic procedure, the anatomy of the ductal system was examined and 285/326 (87.4%) of the hilums were noted to be widened like a basin. The anatomy of the duct from the replicated casts demonstrated a treelike structure and the basin-like widening of the hilum was found in all the excised submandibular glands.

Using sialoendoscopy, a high number of patients presenting with sialolithiasis in the submandibular gland seem to have an anatomical variance in the hilar region. The reproduced ductal system from excised glands also demonstrated this abnormal widening of the hilum. Although further studies need to be performed, we try and explain why there is such a high prevalence of hilar widening in patients with submandibular sialolithiasis.