Abstract Objective To investigate the clinical and pathological features of nodular fasciitis (Nodular fasciitis, NDF), subtypes and immune phenotype. The method of application of light microscopy, immunohistochemistry was observed 35 cases of NDF histopathological features and analysis of clinical data and review of literature. Results NDF more common in young adults aged 20 to 40; occur in the systemic subcutaneous tissue, common in the upper limbs and trunk; rapid and smaller growth characterized by clinical manifestations. The most common the clinical subtypes subcutaneous type. Histopathological features of active proliferation of fibroblasts was bundle, half swirling or S-shaped arrangement, pleomorphic cells, nuclear fission is easy to see; loose myxoid matrix; rich in blood vessels and extravasation of red blood cells, as well as irregular organizational fissures. The histological subtype type: mucus-type (10 cases), granulomatous (15 cases), giant cell type (two cases), fibrous tumor type (n = 8), respectively, to reflect the lesions early, middle and late. Immune phenotypic Vimentin, SMA, MSA positive expression, S-100 and CD34 negative expression. Conclusion NDF A fibroblasts / myofibroblasts hyperplastic lesions, pathological complex, diverse ingredients are familiar with the clinical features and histological configuration can avoid misdiagnosed as sarcoma.

Key words nodular fasciitis; histopathological; immune phenotype

    Nodular fasciitis (NDF) is a self-limiting reaction (muscle) fiber mother cell proliferative lesions [1], clinical but few reports are not uncommon, often misdiagnosed as sarcoma, also known as “pseudosarcomatous fasciitis. " This paper reports 35 cases and literature review of its clinical and pathological features, subtypes and immune phenotype analysis.

    1 Materials and methods

    Collection of Tianmen, Hubei Hospital and Tumor Hospital of Hubei Province from January 1995 to December 2005 the pathological diagnosis NDF 35 cases, all surgical specimens. The specimens were fixed in 10% formalin, paraffin section, HE staining, light microscopy. 17 cases of EV two-step method using immunohistochemical antibody Vimentin in MSA, SMA, CD68, CD34, S-100 kit purchased from Fuzhou taking of new biotechnology companies.

    2 Results

    2.1 Clinical data

    NDF in 35 cases including 19 males and 16 females. The age of onset is 20 to 58 years, an average of 34.6 years, of which 20 to 40 years old accounted for 62.5 percent. Occurred in the upper limbs of 24 cases of 16 cases (upper arm, forearm, elbow n = 1), two cases of the lower limbs, torso 7 cases (abdominal wall three cases, chest wall three cases, scapular 1 case), head and breast of each. Tumor size 1 ~ 3cm, the subcutaneous nodules activities. 3 patients had mild pain and tenderness. Duration of 1 week to 1 years. Grow faster at first, then gradually stop growth. Clinical subtypes: 28 cases of the subcutaneous fascia in 5 cases, intramuscular type 1 cases, skull type 1 cases.

    2.2 Pathological examination

    The naked eye can see: tumor size of 1 ~ 3cm, unclear boundaries, no envelope. Cut off-white, and some see the dark red area or myxoid areas.

    Histological observation: morphological variation. The typical case configuration has diagnostic significance: (1) active proliferation of fibroblasts was wispy, semi-vortex-shaped or “S"-shaped arrangement, the tumor nucleus mast lightly stained, pleomorphic obvious. 30 See, for example, mitotic index, and no cases of pathologic nuclear fission; (2) loose myxoid matrix: In addition to the cell density, at least part of the area loose myxoid was feathery structure or tissue culture-like growth; (3) extravasation of red blood cells: fibroblasts beam rich in small blood vessels and tiny bleeding; (4) often irregular fissures or small sac seen in tissue cell-like cells. The addition still visible nascent capillaries and inflammatory cell infiltration, proliferation of collagen bundles hyalinization change.

    Histological subtype: this group of patients based on pathological features four subtypes: (1) the mucus type (10 cases): mucus matrix, the proliferation of fibroblast nuclei were oval, vacuolization, nuclear fission, inflammatory cells less. (2) granulomatous (15 cases): an increase in the proliferation of fibroblasts and new capillaries, more collagen fibers were streak and bundle distribution, inflammatory cell infiltration. (3) the fibroma-type (n = 8): fibroblasts rich, clear glass-like fibrosis, some forms characteristic scar fibers. (4) giant cell type (2): more scattered multinucleated giant cells.

    2.3 immunohistochemistry

    17 cases immunohistochemistry results: of Vimentin, SMA, MSA showed positive expression of CD34, S  100 was negative, and seven cases were CD68-positive (2 cases of giant cell type were positive). Immunohistochemical staining results suggest myofibroblastic differentiation.

    3 Discussion

    Nodular fasciitis, also known as “false sarcoma fasciitis, neither inflammation nor is it true tumor misdiagnosed as malignant [2  4] It is reported that the misdiagnosis rate of 50%, of which 20% overdiagnosis sarcoma [3]. The group had two cases misdiagnosed as fibrosarcoma, 1 was misdiagnosed as mucus liposarcoma.

    Clinically, NDF has two important characteristics of the rapid growth and smaller, [2,5], the duration of mostly not more than 1 to 2 months, and the size is generally less than 2cm, almost no more than 5cm. Each age group can occur, but is more common in young adults. This group of patients are single nodules, size 1 ~ 3cm, the majority formed in a state of confusion activities of subcutaneous nodules. 20 to 40 years old accounted for 62.5%. Older patients with general medical history is also longer, but from the beginning it was fast growth, and thereafter gradually stop growth. The common sites were the upper limbs, torso and head and neck, head and neck are more common in children [1,3]. Rare parts of the blood vessels within the skull, eyelids, vulva, parotid, oral, joints, breast, etc.. The group of 35 patients, consistent with those reported in the upper limbs in 24 patients (68.6%), and seven cases torso. Dayan [6] reported the oral mucosa NDF peak incidence of 30 to 40 years old (more than occurred in other parts of the NDF decade later). The most common site was the buccal mucosa (52.8%) and lips (16.7%), and the course of the disease, nearly 61% of patients with disease duration of more than one month, from 3 days to 2 years more NDF than occurred in other parts of the course of the disease.

    Enzinger nodular fasciitis is divided into three types, namely subcutaneous type intramuscular and fascia type. Other rare special type the skull type fasciitis, of intravascular fasciitis and ossifying fasciitis [1  3]. Three types most common in subcutaneous type, this group accounted for 80.0% (28/35). The five cases fascia along lobular interval growth, infiltration in adipose tissue, the formation of nodules of irregular stellate projections. One cases of intramuscular lesions located 3cm in diameter oval muscle mass. The skull type accompanied skull involvement. Head type is mainly found in the two-year-old baby, occur in the baby boy, mainly involving the skull plate and adjacent scalp soft tissue, and can spread down through the skull plate into the meninges [2]. X display osteolytic defects the surrounding often hardened edge. Around the lesions containing bone fragments [3] In addition to fibroblast proliferation. Intravascular fasciitis is rare and occurs in less than 30 years old. Mainly located in the subcutaneous tissue, involving small and medium-large blood vessel wall and lumen, often involving the vein, occasionally involving arterial or arteriovenous simultaneously involved [2]. Sometimes in whole or in part, into the endovascular single nodule, sometimes multinodular, plexiform or snake-like, a better prognosis. Ossifying fasciitis sometimes nodular fasciitis, and myositis ossificans two image, but the myositis ossificans mature bone with. Sometimes nodular fasciitis an image associated with ossification of Health.

    Latest reported in the literature [7], intra-articular NDF occurs most often in young people knee than subcutaneous or intramuscular NDF long history of collecting 10 cases: seven cases of knee, hand, ankle; 6 males 4 females; median age of 33 years (9 to 50 years old). Lesion size 2 ~ 4cm (average 2.6cm). The disease is easily misdiagnosed as giant cell tumor of tendon sheath, pigmented villonodular synovitis, synovial chondromatosis, inflammatory arthritis such as the and immunohistochemical phenotype consistent with typical NDF.

    NDF histomorphological complex, diverse composition, histological configuration: (1) hyperplasia (myo) fibroblasts form a semi-spiral-shaped or S-shaped configuration; (2) loose myxoid matrix background; (3 ) rich in blood vessels and red blood cell extravasation; (4) irregular tissue fissures or small sac; (5) mitotic common but no pathological mitosis; (6) the proliferation of capillaries and inflammatory cell infiltration, generally but not plasma cells and neutrophils; (7) hyperplasia associated with edema and mucus becomes interstitial collagen or collagen bundles hyalinization; (8) Common multinucleated osteoclast-like giant cells. The above ingredients are different in different cases and different regions of the same case are (1) to (4) with diagnostic significance [4]. We believe that the general diagnosis is not too difficult to grasp the configuration characteristics, combined with clinical young (20 to 40 years old), the lesion is small (less than 2cm), short duration (2-4 weeks) and the location of shallow (subcutaneous more common) . The NDF histological types are generally divided into mucinous, granulomatous type fibroma type of, this may reflect the different periods of the lesions early, mid-and late [3]. Reported in the literature there is wealth to the cell type, giant cell type, repair, metaplasia, hyperplasia and eosinophilic fasciitis subtypes understand the various subtypes polymorphism identification NDF help. More mitotic and invasive border, due to the rapid growth of this disease, the cells are very rich, often misdiagnosed as sarcoma. However, the course of the disease is often shorter superficial tumor location, low magnification wide collagen with visible wavy (half spiral-shaped or S-shaped), red blood cell extravasation, but not pathological mitosis can be the difference between the so called “false sarcoma . " The differential diagnosis includes the dermatofibrosarcoma protuberans sarcoma, fibrosarcoma, mucus liposarcoma, malignant fibrous histiocytoma, cutaneous neurofibromas, skin myxoma etc..

    The nodular fasciitis real cause is not yet clear, various views are still inconsistent. 10% to 15% in patients with a history of trauma seem to support the reactive nature of the lesion. Studies have detected the nodular fasciitis exist 15p11.2, 16p11.2 and 16p13.3 clonal rearrangement, suggesting a benign tumor rather than reactive lesions [8]. Another study using the HUMARA methylation-specific PCR technology to of nodular fasciitis polyclonal cells constitute mucinous cells, fibrous tumor-like lesions were detected, nodular fasciitis is indeed the reactive lesions [9].

    The nodular fasciitis immune phenotype, Vimentin, SMA, MSA was positive, desmin, S-100 and keratin negative, essentially support the differentiation of myofibroblasts.