Plexiform fibrohistiocytic tumor of bone

Abstract

Plexiform fibrohistiocytic tumor is an extremely rare soft tissue tumor with a low malignancy potential. The patient is usually a child or a young adolescent and the tumor is usually localized in the upper extremities. We report on a case of a 21-year old male with a plexiform fibrohistiocytic tumor in the left fibula admitted to our hospital due to a swelling and pain in the left lower extremity. Radiologically a lytic lesion in the distal end of left fibula consistent with a non-aggressive lesion with low biological activity was found. Treated with curettage, the specimen revealed plexiform proliferation of mononuclear histiocyte-like cells, multinucleated osteoclast-like cells, and spindle fibroblast-like cells in variable proportions histopathologically. Immunohistochemical stains were positive for CD68 in scattered fashion in histiocytes and giant cells, and spindle like cells showed positivity for smooth muscle actin. Under electron microscopy, rough endoplasmic reticulum and collagen bundles in the spindle cells suggested fibroblastic differentiation. Also multiple large electron-dense lysosomal granules in histiocytoid cells were found. Multinucleated giant cells exhibited osteoclast-like appearance. All these findings suggested plexiform fibrohistiocytic tumor. Interestingly, the tumor was localized in bone. During the follow up for 27 months after the resection, there was no recurrence or metastasis.

Tumor Fibro-histiocítico Plexiforme de Vulva: Relato de Caso

“…Apesar de estar incluído no subgrupo de tumor fibro--histiocítico, acredita-se que a origem celular do tumor sejam miofibroblastos com potencial de transformação em fibroblastos ou células semelhantes a histiócitos. Estudos ultraestruturais e análises imuno-histoquímicas indicam propriedades celulares (mio)fibroblásticas e histiocíticas 5 .…”

“…Povýsil e Habanec 11 relataram um período de acompanhamento de seis anos sem recorrência. Já Yalcinkaya et al 5 descreveram seguimento por 27 meses de paciente após ressecção inicial, se encontrando bem e sem recorrência.…”

“…Sua taxa de recorrência varia de 12,5% a 40%, com relatos de metástases linfonodais e pulmonares 1,3,4 . Embora afete proeminentemente o tecido adiposo subcutâneo, esse tumor maligno também pode afetar o osso 5 .…”

Plexiform fibrohistiocytic tumor: imaging features and clinical findings

“…PFHT is more common in females and typically presents in children and young adults [1,4] as a small, slow-growing, asymptomatic soft tissue nodule or flattened, indurated plaque of firm consistency [4]. The most common site is the upper extremity [1], with all but one previously reported PFHT being located in the subcutaneous adipose tissue with extension into the dermis, skeletal muscle, or both [4]; a single case of an osseous PFHT, within the left fibula, has been reported [7]. Unlike the single case of PHFT illustrated in the article by Ng et al [6], in which the patient had paraneoplastic hypophosphatemia, none of our patients exhibited a paraneoplastic syndrome.…”