Pleomorphic hyalinizing angiectatic tumour of soft parts: a case report and review of the literature

Pleomorphic hyalinizing angiectatic tumour (PHAT) is a recently described, rare, low-grade soft tissue neoplasm. The lesion is characterized by clusters of hyalinized and thrombosed ectatic vessels alternating with a variably cellular stroma composed of atypical cells, many with intranuclear pseudoinclusions. Other features are inflammatory cell infiltration, haemosiderin deposits, focal calcificationand minimal to absent mitoses. No metastases have so far been described; however, the local recurrence rate has been found to be high. To date, approximately 60 such cases of PHAT and its precursor, “early PHAT”, have been described in the world literature. We report the first known case of PHAT from this institution which occurred in the left loin of a 77-year old woman. Three years previously, a smaller lesion excised from the same location had been called an ancient schwannoma on histology. This is the most commondifferential diagnosis offered for this entity even though the two differ in immunohistochemical profile. 'Early PHAT' was also identified on the periphery of the recurrent lesion. El tumor pleomorfico hialinizante angioectasico (TPHA) – entidad rara, de reciente descripcion – es un neoplasma del tejido blando, de bajo grado. La lesion se caracteriza por la presencia de racimos de vasos ectasicos trombosados e hialinizados, que alternan con un estroma celular variable compuesto de celulas atipicas, muchas de ellas con pseudoinclusiones intranucleares. Otrascaracteristicas son: la infiltracion celular inflamatoria, los depositos hemosiderinicos, la calcificacionfocal, y la mitosis minima o ausente. Hasta el presente no se han descrito metastasis. Sin embargo, se ha hallado que la tasa de recurrencia local es alta. Hasta la fecha, aproximadamente 60 de estos casos de TPHA y su precursor el “TPHA temprano”, han sido descritos en la literatura mundial. Reportamosel primer caso de TPHA conocido de esta institucion – una anciana de 77 anos de edad, a quien se le presento en la region lumbar izquierda. Tres anos antes, una lesion mas pequena extirpada del mismolugar, hubiera sido llamada un schwannoma antiguo en histologia. Este es el diagnostico diferencial mas comun ofrecido para esta entidad, aun cuando los dos difieren en cuando a perfilimunohistoquimico. El TPHA temprano fue identificado tambien en la periferia de la lesion recurrente.