Journal of Cytology
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Year : 2012  |  Volume : 29  |  Issue : 4  |  Page : 264-266
Fine needle aspiration cytology of pseudosarcomatous reactive lesions of soft tissues: A report of two cases

Department of Pathology, JSS Medical College, JSS University, Mysore, Karnataka, India

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Date of Web Publication28-Nov-2012


Pseudosarcomatous lesions are reactive proliferative lesions of the soft tissue, that are likely to be misdiagnosed as malignant, based on clinical and histological features. The most common lesions are nodular fasciitis, proliferative fasciitis, proliferative myositis and myositis ossificans. These rapidly growing soft-tissue lesions can represent a variety of diagnoses involving radically different treatment modalities. Accurate diagnosis is important to avoid unnecessary and often mutilating surgery. We report two cases to illustrate the importance of correct identification of these lesions by fine needle aspiration cytology.

Keywords: Fine needle aspiration cytology; nodular fasciitis; proliferative myositis; pseudosarcomatous lesions

How to cite this article:
Satish S, Shivalingaiah SC, Ravishankar S, Vimalambika MG. Fine needle aspiration cytology of pseudosarcomatous reactive lesions of soft tissues: A report of two cases. J Cytol 2012;29:264-6

How to cite this URL:
Satish S, Shivalingaiah SC, Ravishankar S, Vimalambika MG. Fine needle aspiration cytology of pseudosarcomatous reactive lesions of soft tissues: A report of two cases. J Cytol [serial online] 2012 [cited 2023 Feb 7];29:264-6. Available from:

   Introduction Top

Nodular fasciitis (NF), proliferative fasciitis (PF) and proliferative myositis (PM) are reactive lesions that typically resolve spontaneously. [1] The clinical course is completely benign, but the high risk of misinterpreting these lesions as malignant owing to its rapid growth, high cellularity and high mitotic activity on histology has been well documented. [2] These lesions are also a major diagnostic pitfall in fine needle aspiration cytology (FNAC). [3] As FNAC of soft tissue lesions is becoming more widely accepted, it is important to recognize the cytological features of these reactive lesions. [4]

   Case Reports Top

Case 1

A 65-year-old man presented with a hard mass measuring 4 × 3 cm in the supraclavicular region. Clinical diagnosis was secondaries in the lymph node. FNAC was performed. The smears were moderately cellular and showed proliferative spindle cells among the skeletal muscle fibers. Good number of uni and multinucleated cells having enlarged and atypical nuclei were seen. Giant cells were conspicuous [Figure 1]a and b. A diagnosis of metastatic tumor was made. The patient underwent various tests, but no primary was detected. The mass was excised. Grossly, the mass was grey-white and measured 3×2 cm. On histopathology, there were skeletal muscle fibers and fibro-collagenous tissue with chronic inflammatory cells, proliferating fibroblasts and giant cells. Giant cells had abundant dense eosinophilic cytoplasm and vesicular nuclei with prominent nucleoli. The features were consistent with a diagnosis of proliferative myositis.
Figure 1: (a) Smear shows spindle cells among skeletal muscle fibers (H and E, x100). (b) Cells having enlarged, atypical nuclei (MGG, x200). (c) Ganglion-like cells (Pap, x400)

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Case 2

A 29-year-old man presented with a firm mass measuring 2.2 × 2 cm in the upper neck of one week duration. FNAC was done. The aspirate was cellular and showed a polymorphous population of isolated and sheets of spindle cells with inflammatory cells consisting of lymphocytes, plasma cells, eosinophils and neutrophils. The nuclei of some of the cells were slender with pointed ends, while others had round to oval nuclei, with evenly distributed fine chromatin. A few muscle giant cells and ganglion-like cells of triangular to polyhedral shapes were seen. The background was myxoid. [Figure 1]c A diagnosis of NF was made. The mass resolved after three weeks with no further treatment.

   Discussion Top

The potential of FNAC as a diagnostic tool in the evaluation of soft tissue lesions is becoming increasingly evident as usage becomes widespread. Benign spindle cell proliferations of soft tissue can be exceptionally difficult to correctly interpret and subclassify using FNA-based smears. This is particularly true for benign lesions that paradoxically mimic sarcoma. [2] Pseudosarcomatous soft tissue lesions, are further, a major diagnostic pitfall in the FNAC of spindle cell lesions. [3] The dilemma is compounded when such pseudosarcomatous lesions occur in uncommon sites or has unusual characteristics. [2]

NF, PF and PM are a closely related group of self-limiting, benign proliferative lesions of fibroblasts and myofibroblasts of unknown cause. The FNAC features of NF and PF are essentially the same, except that PF shows lower cellularity, more collagen fragments, and abundant ganglion-like cells. PM lesions are rather deep in location. [1] Cytologically, the aspirates are moderately cellular with a mixture of isolated cells and sheets of closely packed spindled fibroblast-like cells. PM differs from NF in two ways: (1) the proliferative spindle cells are situated among skeletal muscle tissue and (2) the giant ganglion-like cells are more abundant. [3]

The reasons for misdiagnosis in the first case were: (1) the age of the patient and location of the lesion (2) failure to recognize the importance of spindle cells within the skeletal muscle fibers and (3) misinterpretation of muscle giant cells as normal skeletal muscle fibers and ganglion-like cells with reactive atypia as malignant cells.

NF is the most common pseudosarcomatous proliferative lesion of soft tissues that seldom recurs. [5] Unlike soft tissue neoplasms which require surgical excision for treatment, NF can resolve spontaneously. [2],[3] It is well established that pseudosarcomatous proliferative lesions of soft tissue usually present as small, superficial nodules with rapid growth and short duration in contrast to the fairly deep, large masses and long duration of sarcomas. [3] Cytologically, a polymorphic pattern of cells, high cellularity, abundant isolated cells and ganglion-like cells with benign looking nuclei are the most characteristic features. [1] Inflammation varies from minimal to marked and consists of neutrophils, lymphocytes, eosinophils, histiocytes and/or multinucleated giant cells. [4] Granuloma-like cytological features, with numerous multinucleated giant cells have been reported. [1] Given its variable morphological appearance, ranging from myxoid to fibrous, NF can be difficult to distinguish from soft tissue neoplasms [4] and NF is considered as the first diagnostic pitfall in the FNAC of spindle cell lesions. [6]

In our case, although the site in the neck was rare, a short clinical history, the correct identification of reactive nature of the spindle cells, ganglion-like cells and muscle giant cells in an inflammatory background was crucial in making the correct diagnosis. Spontaneous resolution provided objective evidence that the FNAC diagnosis was correct, thus avoiding unnecessary surgery.

Immunohistochemical stains can further provide diagnostic support. These studies can be done on fresh aspirate smears, destained slides or cell block material. Since NF can exhibit fibrohistiocytic, as well as myofibroblastic differentiation, smooth muscle actin and CD68 can be useful. [4]

In conjunction with clinical course, FNAC is a helpful diagnostic tool to differentiate pseudosarcomatous proliferative lesions of soft tissue from true sarcomas. When the clinical data and FNAC features are typical of NF, PF or PM, the patient should be managed nonsurgically first with follow-up. If regression does not occur within four to eight weeks, surgery should be performed. [3]

It is well known that NF, PF and PM are self-limiting diseases. The cytological diagnosis of these lesions can be challenging. In spite of atypical nuclei, fine chromatin, smooth nuclear membranes, giant cells and inflammatory cells should guide the pathologist towards a correct diagnosis. A correct identification on FNAC will obviate the need for radical surgery with its attendant complications.

   References Top

1.Wong NL, Di F. Pseudosarcomatous fasciitis and myositis: diagnosis by fine-needle aspiration cytology. Am J Clin Pathol 2009;132:857-65.  Back to cited text no. 1
2.Plaza JA, Mayerson J, Wakely PE Jr. Nodular fasciitis of the hand: a potential diagnostic pitfall in fine-needle aspiration cytopathology. Am J Clin Pathol 2005;123:388-93.  Back to cited text no. 2
3.Wong NL. Fine needle aspiration cytology of pseudosarcomatous reactive proliferative lesions of soft tissue. Acta Cytol 2002;46:1049-55.  Back to cited text no. 3
4.Kong CS, Cha I. Nodular fasciitis: diagnosis by fine needle aspiration biopsy. Acta Cytol 2004;48:473-7.  Back to cited text no. 4
5.Bernstein KE, Lattes R. Nodular (pseudosarcomatous) fasciitis, a nonrecurrent lesion: clinicopathologic study of 134 cases. Cancer 1982;49:1668-78.  Back to cited text no. 5
6.Powers CN, Berardo MD, Frable WJ. Fine- needle aspiration biopsy: pitfalls in the diagnosis of spindle-cell lesions. Diagn Cytopathol 1994;10:232-40.  Back to cited text no. 6

Correspondence Address:
Suchitha Satish
#892, I Block, 1st cross, Ramakrishnanagar, Mysore, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9371.103949

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