[Histological, immunohistochemical and molecular study of a paratesticular dedifferentiated liposarcoma with inflammatory myofibroblastic tumor-like features]. / Liposarcoma desdiferenciado paratesticular simulando un tumor miofibroblástico inflamatorio. Estudio histológico, inmunohistoquímico y molecular.

We report the histological, immunohistochemical, and molecular findings of a dedifferentiated liposarcoma with inflammatory myofibroblastic tumor-like features occurring in the paratesticular region. Histologically, the dedifferentiated component closely resembled an inflammatory myofibroblastic tumor. The neoplastic cells were positive for smooth muscle actin with focal CD56, CD99, Bcl2 and EMA expression. WT1, calretinin, myogenin, CK(AE1/AE3), desmin, H-caldesmon, CD34, ALK, CKIT, DOG1, MUC4 and STAT6 were negative. MDM2 showed diffuse and strong nuclear positivity in neoplastic cells and fluorescence in situ hybridization (FISH) revealed amplified MDM2 (high level) but no SYT rearrangement. Although a lipomatous component was evident macroscopically, well-differentiated liposarcomatous components were not evident in the section examined. Dedifferentiated liposarcoma can have prominent inflammatory myofibroblastic tumor-like features. Pathologists should be aware of this histological variant in order to avoid misdiagnosing dedifferentiated liposarcoma as inflammatory myofibroblastic tumor or other spindle cell tumors which have different behavioral patterns and treatment requirements.

Liposarcoma desdiferenciado paratesticular simulando un tumor miofibroblástico inflamatorio. Estudio histológico, inmunohistoquímico y molecular / Histological, immunohistochemical and molecular study of a paratesticular dedifferentiated liposarcoma with inflammatory myofibroblastic tumor-like features

Se presenta un estudio histológico, inmunohistoquímico (IHQ) y molecular de un liposarcoma desdiferenciado paratesticular remitido a nuestro centro, con hallazgos histológicos similares a un tumor miofibroblástico inflamatorio. Las células tumorales fueron positivas para actina músculo liso (AML) y focalmente positivas para CD56, CD99, Bcl2 y EMA. La expresión de WT1, calretinina, miogenina, CK(AE1/AE3), desmina, H-caldesmona, CD34, ALK, CKIT, DOG1, MUC4 y STAT6 fue negativa. MDM2 mostró positividad nuclear intensa y difusa por IHQ y alto nivel de amplificación génica mediante hibridación fluorescente in situ (FISH). La FISH no reveló reordenamiento del gen SYT. En el estudio histológico del corte remitido no encontramos evidencias de componente liposarcomatoso bien diferenciado, aunque el aspecto macroscópico de la pieza lo sugería. El liposarcoma desdiferenciado puede presentar hallazgos histológicos que recuerdan a un tumor miofibroblástico inflamatorio y que expanden el espectro histológico de esta variante de liposarcoma. El conocimiento de la existencia de esta variante de liposarcoma es de crucial importancia para no confundirla con otras neoplasias que, aunque histológicamente similares, difieren en la evolución clínica y/o tratamiento.(AU)

We report the histological, immunohistochemical, and molecular findings of a dedifferentiated liposarcoma with inflammatory myofibroblastic tumor-like features occurring in the paratesticular region. Histologically, the dedifferentiated component closely resembled an inflammatory myofibroblastic tumor. The neoplastic cells were positive for smooth muscle actin with focal CD56, CD99, Bcl2 and EMA expression. WT1, calretinin, myogenin, CK(AE1/AE3), desmin, H-caldesmon, CD34, ALK, CKIT, DOG1, MUC4 and STAT6 were negative. MDM2 showed diffuse and strong nuclear positivity in neoplastic cells and fluorescence in situ hybridization (FISH) revealed amplified MDM2 (high level) but no SYT rearrangement. Although a lipomatous component was evident macroscopically, well-differentiated liposarcomatous components were not evident in the section examined. Dedifferentiated liposarcoma can have prominent inflammatory myofibroblastic tumor-like features. Pathologists should be aware of this histological variant in order to avoid misdiagnosing dedifferentiated liposarcoma as inflammatory myofibroblastic tumor or other spindle cell tumors which have different behavioral patterns and treatment requirements.(AU)

Enfermedad de Rosai-Dorfman con presentación cutánea y ausencia de mutaciones BRAF-V600, KRAS y NRAS: ¿trastorno neoplásico o reactivo / Cutaneous Rosai-Dorfman disease with lack of BRAF-V600, KRAS or NRAS mutations: A reactive or neoplastic disorder?

Las histiocitosis de células no Langerhans, como la enfermedad de Rosai-Dorfman (ERD) y el xantogranuloma, son trastornos raros que pueden mostrar solapamiento de los hallazgos histopatológicos e inmunohistoquímicos. En el presente estudio describimos un caso clínico de una paciente femenina de 53años con placas eritematoso-violáceas en las mejillas y edema en los pabellones auriculares. Se realizó una biopsia y en el examen histopatológico se observó una proliferación de histiocitos con emperipolesis característica de la ERD junto con un infiltrado linfoplasmocítico. El estudio inmunohistoquímico mostró que la mayoría de los histiocitos fueron positivos para S100 y CD68, y negativos para CD1a, lo que confirmó el diagnóstico de ERD. El análisis molecular no detectó la mutación BRAF-V600, NRAS ni KRAS. Se discute el diagnóstico diferencial entre las histiocitosis no de células de Langerhans con presentación cutánea. El patólogo debe estar al tanto de las presentaciones clínicas o patológicas inusuales de la ERD, y en los pacientes con enfermedad no resecable/escasamente resecable o resistentes al tratamiento clásico de la ERD deberían explorarse otras opciones terapéuticas basadas en los resultados de los estudios moleculares.(AU)

Non-Langerhans cell histiocytosis, including Rosai-Dorfman disease (RDD) and xanthogranuloma are rare disorders with occasional overlapping in the histopathological and immunohistochemical (IHC) findings. We report the case of a 53-year-old woman with erythematous-violaceous plaques on the cheeks and edema in the auricular pavilions. A biopsy was performed and the histopathological examination revealed a histiocytic proliferation with emperipolesis characteristic of RDD and lymphoplasmocitic infiltrate. IHC analysis showed S100 and CD68 positivity in the histiocytes but was negative for CD1a, supporting the diagnosis of RDD. Molecular analysis failed to detect BRAF-V600, NRAS or KRAS mutation. We discuss the differential diagnosis of cutaneous non-Langerhans cell histiocytosis. Pathologist must be aware of unusual presentations of RDD and further treatment options must be explored for patients with unresectable lesions and/or resistance to the classical management of RDD.(AU)

[Cutaneous Rosai-Dorfman disease with lack of BRAF-V600, KRAS or NRAS mutations: A reactive or neoplastic disorder?] / Enfermedad de Rosai-Dorfman con presentación cutánea y ausencia de mutaciones BRAF-V600, KRAS y NRAS: ¿trastorno neoplásico o reactivo.

Non-Langerhans cell histiocytosis, including Rosai-Dorfman disease (RDD) and xanthogranuloma are rare disorders with occasional overlapping in the histopathological and immunohistochemical (IHC) findings. We report the case of a 53-year-old woman with erythematous-violaceous plaques on the cheeks and edema in the auricular pavilions. A biopsy was performed and the histopathological examination revealed a histiocytic proliferation with emperipolesis characteristic of RDD and lymphoplasmocitic infiltrate. IHC analysis showed S100 and CD68 positivity in the histiocytes but was negative for CD1a, supporting the diagnosis of RDD. Molecular analysis failed to detect BRAF-V600, NRAS or KRAS mutation. We discuss the differential diagnosis of cutaneous non-Langerhans cell histiocytosis. Pathologist must be aware of unusual presentations of RDD and further treatment options must be explored for patients with unresectable lesions and/or resistance to the classical management of RDD.