Fine needle aspiration cytology of plexiform fibrohistiocytic tumor. A case report

Approach to Fine Needle Aspiration of Giant Cell-rich Tumors of Soft Tissue

Giant cells may be found in a wide variety of reactive and neoplastic soft tissue lesions. Because of their distinct histomorphology, they often stand out in procured samples such as fine needle aspirates. The giant cells themselves may be benign or neoplastic. However, the presence, type, and quantity of giant cells are usually not specific and in some cases can even be misleading when making a diagnosis. The aim of this review is to guide the practicing cytopathologist in narrowing their differential diagnosis when encountering one of these challenging giant cell-rich lesions of the soft tissue.

Fine needle aspiration cytology of paediatric soft tissue tumours highlighting challenges in diagnosis of benign lesions and unusual malignant tumours

INTRODUCTION

The type of soft tissue lesions seen in children differs from that seen in adults. The role of fine needle aspiration (FNA) cytology in their diagnosis is not well documented.

AIM

To study the cytopathological spectrum of paediatric soft tissue tumours to highlight uncommon benign and malignant lesions and the challenges in their diagnosis.

METHODS

A 3-year retrospective audit of all paediatric soft tissue FNA cytology cases from 2015 to 2017 was performed. Smears were reviewed along with cell block immunocytochemistry and follow-up histopathology of resected specimens wherever available.

RESULTS

A total of 127 cases were reviewed, which included 72 benign and 55 malignant soft tissue tumours. Uncommon lesions described herein are myxoid fibrohistiocytic tumour, myxoma, lipoblastoma, Bednar tumour, malignant extra-renal rhabdoid tumour and desmoplastic small round cell tumour. Histopathology confirmation was available in 25 cases, out of which 16 cases were completely concordant. In eight cases, all benign diagnoses, histopathology provided more accurate subtyping than FNA. These included cases of lipoblastoma, myxoma and spindle cell haemangioma.

CONCLUSION

FNA cytology of paediatric soft tissue tumours is accurate in classifying lesions as benign or malignant which helps in treatment planning. Immunocytochemistry performed on cell blocks is useful for subtyping malignant lesions.

Plexiform fibrohistiocytic tumor on the chest of a 5-year-old child and review of the literature

Plexiform fibrohistiocytic tumor (PFT) is a rare neoplasm of mesenchymal origin that can be identified by its propensity for children and adolescents combined with a characteristic histologic arrangement of histiocytes and osteoclast-like giant cells whorled within tumor islands. A 5-year-old female presented with a raised, intermittently tender, and slowly enlarging tumor on her chest, which was histologically confirmed to be a PFT. We present this case along with a comprehensive review of PFT cases reported in the literature to describe the demographic, histologic, and rarely metastatic behavior of this entity. It is important to include PFT on the differential diagnosis of an enlarging tumor in the pediatric population.

Plexiform Fibrohistiocytic Tumor Presenting as a Central Neck Mass Clinically Mimicking a Thyroglossal Duct Cyst: An Unusual Case Reported with Histo-cytopathologic Correlation and a Review of the Cytopathology Literature

We present the case of an uncommon example of a plexiform fibrohistiocytic tumor (PFHT) occurring in the anterior central neck region of a 40 year-old female with previous subtotal thyroidectomy. The tumor clinically mimics a complicated thyroglossal duct cyst. On fine needle aspiration cytology, the tumor was composed of sheets of bland spindle cells and nests of plump histiocytoid cells in vaguely whorled arrangements. Occasional multinucleated giant cells were also identified. The excised specimen showed an irregular, highly infiltrative subcutaneous tumor arranged in a nodular/plexiform pattern concentrated to the center of the tumor mass. In addition, the tumor contained numerous tongue-like extensions composed of variably cellular, fibroblastic/fibromatosis-like areas. These fibroblastic/fibromatosis-like extensions reached far from the epicenter of the tumor and were associated with scattered small plexiform nodules of histiocytic cells. These tongue-like extensions multifocally involved the surgical margins. The fibroblastic and histiocytoid cells showed diffuse smooth muscle actin (SMA) expression. The multinucleated giant cells and also the histiocytoid proliferation were positive for CD68. This case illustrates an uncommon both anatomical and demographic manifestation of PFHT and also characterize the fine needle aspiration cytologic features in this tumor, which previously have been reported in a few cases.

Fine-needle aspiration cytology features of a recurring plexiform fibrohistiocytic tumor in the upper limb and review of the literature

Plexiform fibrohistiocytic tumor is a rare soft tissue tumor that has a propensity to occur in the extremities in adolescents and young adults. Its cytologic features are not well documented, with only two case reports available in the literature. We present the case of a recurrent plexiform fibrohistiocytic tumor in a 19-year-old male, the cytologic features of which mimic that of a high-grade sarcoma. We discuss the likely differential diagnosis based on the cytologic findings and a review of the current literature on this highly unusual tumor is also performed.

Plexiform fibrohistiocytic tumor: a brief review

Plexiform fibrohistiocytic tumor is a rare mesenchymal neoplasm of intermediate malignancy, first reported by Enzinger and Zhang in 1988. It has a predilection for children and young adults but can occur at any age. The tumor usually involves the upper limbs as a slow-growing, painless mass. The tumor has a high local recurrence rate but metastasizes only rarely. Histologically, the tumor is characterized by poorly demarcated dermal or subcutaneous mass with multinodular plexiform growth and fibrohistiocytic cytomorphology. There are three distinct recognized growth patterns: fibrohistiocytic, fibroblastic, and mixed types. The tumor displays uniform immunoreactivity for vimentin and CD68. Ultrastructurally, the tumor cells have features of myofibroblasts and histiocyte-like cells. Complete surgical resection of the tumor, preferably with wider margins, is required to prevent local recurrence. Long-term follow-up is necessary to detect any nodal or pulmonary metastasis.

Plexiform fibrohistiocytic tumor in three children

Plexiform fibrohistiocytic tumor is a very rare fibrohistiocytic tumor of intermediate malignancy. It can occur at any age but is more prevalent in children and in young adults. Here we present the clinicopathologic findings of three girls with this tumor. The patients were 8 months, 14 months, and 7 years of age. They each presented with a solitary, nontender, subcutaneous nodule or plaque. Light microscopy and immunohistochemical study findings were compatible with plexiform fibrohistiocytic tumor. We also review the previously published cases in the English-language literature.

Cytologic spectrum of 227 fine-needle aspiration cases of chest-wall lesions

This study was carried out with the objective of studying the cytomorphology of the wide variety of chest-wall lesions. Two hundred twenty-seven chest-wall lesions were studied over a period of 4 yr. Routine May-Grünwald-Giemsa (MGG) and hematoxylin-eosin (H&E) slides were studied along with special stains, whenever required. The malignant lesions comprised 36.13% of all cases (81/227). Of the 126 benign lesions, the majority were inflammatory in nature (68/126), the next commonest lesion being lipoma (38/126). Rare cases of tuberculosis involving the sternum, epithelioid leiomyosarcoma, and neuroendocrine tumors involving ribs, malignant nerve sheath tumors involving the chest wall, metastatic carcinoma of the stomach and prostate, and papillary carcinoma thyroid are reported in this series. Histopathology was available in 24 cases, and hematological correlation in one case. A 100% cytohistological and cytohematological correlation was found, with no false positives or false negatives. In conclusion, fine-needle aspiration cytology is a rapid, diagnostic tool, eliciting many interesting lesions in the chest wall. It is useful not only in detecting primary and metastatic lesions, but also in follow-up of tumor recurrence.