[Fat-forming solitary fibrous tumor with NAB2/ STAT6 gene fusion. Case report of genial location and literature review]. / Tumor fibroso solitario variedad lipomatosa con fusión génica NAB2/STAT6. Estudio de un caso de localización geniana y revisión de la literatura.

The lipomatous variety solitary fibrous tumor is a soft tissue neoplasm composed of mature adipose tissue and hemangiopericytoma areas. A 53-year-old man consulted for facial asymmetry and maxillofacial magnetic resonance imaging showed a cystic lesion, 3 x 2 cm in size, in front of the anterior wall of the maxillary sinus. Histologically, there were dense spindle cells expressing CD34, CD99, Bcl-2, and STAT6, myxoid zones, hemangiopericytomatous blood vessels, and S100 positive adipocytes. NAB2/STAT6 gene fusion was revealed by RT-PCR. The main differential diagnosis was raised with the spindle cell lipoma and malignant variant of the lipomatous solitary fibrous tumor. STAT6 overexpression and NAB2/STAT6 gene fusion are specific for lipomatous solitary fibrous tumor and the presence of lipoblasts and atypical lipomatous tumor areas suggests malignancy. These tumors located in the head and neck region have a benign biological behavior.

Tumor fibroso solitario variedad lipomatosa con fusión génica NAB2/STAT6. Estudio de un caso de localización geniana y revisión de la literatura / Fat-forming solitary fibrous tumor with NAB2/ STAT6 gene fusion. Case report of genial location and literature review

El tumor fibroso solitario variedad lipomatosa es una neoplasia de partes blandas compuesta por tejido adiposo maduro y áreas de hemangiopericitoma. Un varón de 53 años se presentó clínicamente con asimetría facial. La resonancia magnética maxilofacial demostró una lesión quística, de 3 x 2 cm, por delante de la pared anterior del seno maxilar. Histológicamente, había áreas fusocelulares densas que expresaban CD34, CD99, Bcl-2 y STAT6, zonas mixoides, vasos sanguíneos hemangiopericitomatosos y adipocitos S100 positivos. La fusión génica NAB2/STAT6 fue revelada mediante RT-PCR. El principal diagnóstico diferencial se planteó con el lipoma de células fusiformes y la variante maligna del tumor fibroso solitario lipomatoso. La sobreexpresión de STAT6 y la fusión génica NAB2-STAT6 son específicas del tumor fibroso solitario lipomatoso y la presencia de lipoblastos y áreas de tumor lipomatoso atípico sugiere malignidad. Estos tumores en cabeza y cuello tienen un comportamiento biológico benigno.(AU)

The lipomatous variety solitary fibrous tumor is a soft tissue neoplasm composed of mature adipose tissue and hemangiopericytoma areas. A 53-year-old man consulted for facial asymmetry and maxillofacial magnetic resonance imaging showed a cystic lesion, 3 x 2 cm in size, in front of the anterior wall of the maxillary sinus. Histologically, there were dense spindle cells expressing CD34, CD99, Bcl-2, and STAT6, myxoid zones, hemangiopericytomatous blood vessels, and S100 positive adipocytes. NAB2/STAT6 gene fusion was revealed by RT-PCR. The main differential diagnosis was raised with the spindle cell lipoma and malignant variant of the lipomatous solitary fibrous tumor. STAT6 overexpression and NAB2/STAT6 gene fusion are specific for lipomatous solitary fibrous tumor and the presence of lipoblasts and atypical lipomatous tumor areas suggests malignancy. These tumors located in the head and neck region have a benign biological behavior.(AU)

Orbital soft tissue composite lymphoma presenting as recurrence of a nodal lymphoma with mantle and follicular cell components: a case report, literature review and guideline for the treatment of patients / Linfoma compuesto de tejidos blandos orbitario presentándose como recurrencia de un linfoma ganglionar con componentes del manto y folicular: descripción de un caso, revisión de la literatura y guía para el tratamiento de los pacientes

Composite lymphoma with mantle and follicular cell components is a challenging diagnosis. Flow cytometry, immunohistochemistry and molecular genetics are required to distinguish the two components, as often the more aggressive one is predominant and masks the other. A 58-year-old man with history of nodal composite lymphoma presented with right exophthalmos and diplopia. A head CT scan showed an orbital tumor. A biopsy of the tumor revealed a mantle cell lymphoma predominating over a follicular lymphoma. Immunoglobulin heavy chain and light chain rearrangements analysis by PCR proved that both components of the orbital tumor were recurrences of the same nodal composite lymphoma diagnosed two years earlier. The nodal lymphoma was composed of a follicular lymphoma and an in situ mantle cell neoplasia. Consensus view is that dominant lymphoma should be treated when needed but taking into account if the mantle cell lymphoma is an in situ neoplasia and if it expresses CD5 and SOX11

El diagnóstico de linfoma compuesto con componentes del manto y folicular es desafiante y requiere de técnicas como citometría de flujo, inmunohistoquímica y genética molecular, porque a menudo el componente linfoide más agresivo predomina sobre el otro, enmascarándolo. Un varón de 58 años con historia de linfoma compuesto ganglionar presentó exoftalmos derecho y diplopia. La TAC de cabeza mostró un tumor orbitario. Una biopsia del tumor reveló un linfoma del manto predominando sobre un linfoma folicular. El reordenamiento genético mediante PCR de la cadena pesada y cadenas ligeras de inmunoglobulina demostró que ambos componentes del tumor orbitario eran recurrentes del mismo linfoma compuesto ganglionar diagnosticado 2 años antes. El linfoma ganglionar estaba compuesto por linfoma folicular y neoplasia del manto in situ. El consenso es que el linfoma dominante debe ser tratado cuando sea necesario considerando si el linfoma del manto es in situ y si expresa CD5 y SOX11

Orbital soft tissue composite lymphoma presenting as recurrence of a nodal lymphoma with mantle and follicular cell components: A case report, literature review and guideline for the treatment of patients.

Composite lymphoma with mantle and follicular cell components is a challenging diagnosis. Flow cytometry, immunohistochemistry and molecular genetics are required to distinguish the two components, as often the more aggressive one is predominant and masks the other. A 58-year-old man with history of nodal composite lymphoma presented with right exophthalmos and diplopia. A head CT scan showed an orbital tumor. A biopsy of the tumor revealed a mantle cell lymphoma predominating over a follicular lymphoma. Immunoglobulin heavy chain and light chain rearrangements analysis by PCR proved that both components of the orbital tumor were recurrences of the same nodal composite lymphoma diagnosed two years earlier. The nodal lymphoma was composed of a follicular lymphoma and an in situ mantle cell neoplasia. Consensus view is that dominant lymphoma should be treated when needed but taking into account if the mantle cell lymphoma is an in situ neoplasia and if it expresses CD5 and SOX11.