Nodular Fasciitis
Key Points
Nodular fasciitis is a rare benign reactive lesion characterized by a proliferation of fibroblasts and myofibroblasts that involve subcutaneous tissue, skeletal muscles, and fascia
It is classified according to the plane of tissue that is primarily involved, including subcutaneous, dermal, intramuscular, and fascial types
The etiology of NF remains unknown but a traumatic etiology has been proposed
Gene rearrangements suggest that nodular fasciitis may be an unusual phenomenon of transient or self-resolving neoplasia
The clinical presentation is usually a skin-colored to light brown firm, smooth, mobile subcutaneous nodule that grows rapidly and measures 1 to 2 cm in diameter
Surgical excision is recommended as the treatment of choice to exclude malignancy, and lesions can be cured with a conservative surgical resection
The prognosis is usually good, and recurrence is exceptionally rare
Nodular fasciitis (NF) is a rare benign reactive lesion of unknown etiology characterized by a proliferation of fibroblasts and myofibroblasts1,2 that involves subcutaneous tissue, skeletal muscles, and fascia.3,4 It was first described by Konwaler and Weiss5 in 1955 as “subcutaneous pseudosarconiatous fibromatosis (fasciitis).” In that report, the authors reported eight cases of a rapidly growing nodule that histologically resembled fibrosarcoma.
NF can appear in any part of the body, but the most common sites of involvement are the upper extremity, followed by the chest and back. Approximately 7% to 20% of cases occur in the head and neck region,6,7,8,9,10,11,12,13 and these cases are more often seen in younger children.6,14,15,16 In the facial region most lesions are located in the skin, parotid gland, and subcutaneous tissues of the mandible and zygoma.7 The eyelid is rarely involved,17,18,19,20,21,22,23,24,25,26,27 but several cases of orbital involvement have been described.22,28,29
There is no clear gender predilection, with reports varying from male and female equivalence, male predominance, to female predominance.7,11,30,31 NF is often initially misdiagnosed as a sarcoma because of its rapid growth and its histologic appearance and has been referred to as pseudosarcomatous fasciitis.8,14,32
Nodular fasciitis can be classified according to the plane of tissue that is primarily involved. These include subcutaneous, intramuscular, and fascial types.7 A fourth variant, the dermal NF, is more commonly found in the head and neck region.2 Among 16 cases of facial NF, all lesions involved subcutaneous tissues, but 7 (43.8%) also involved the muscle layers and 10 (62.5%) had dermal involvement.33
Lesions are usually attached to the fascia from which they arise and extend into the subcutaneous fat. Occasionally they arise from the fibrous septa of the subcutaneous fat and only secondarily extend to the fascia.7 In 1966, based on 17 personal and 314 cases from the literature, Mehregan34 defined the clinical appearance, epidemiology, and histologic findings of NF as a freely mobile, subcutaneous nodule, sparing the dermis, with an aggressive appearing, fibroblast-like histologic picture. Lesions typically grow rapidly, with a duration of <1 month in 57% of cases and >3 months in only 15%. Tenderness or pain was reported in 55% of cases.
Etiology and Pathogenesis
The etiology of NF remains unknown but a traumatic etiology has been proposed.34 In a study of 50 patients with NF, 5 (10%) recalled antecedent trauma.16 In another study of 16 patients with facial NF, 9/16 (77%) had a history of trauma or stimulation before development of the lesion.33 However, most other studies show only a small number of patients who report even a vague history of trauma.5,11,12,31,32,34,35,36,37 Because some cases of nodular fasciitis appear to arise after minor trauma and then spontaneously resolve, it has not been clear whether these lesions arise as a reactive process or as a true neoplasm.38 Erickson-Johnson et al39 reported that 92% of NF tumors contain a gene rearrangement involving USP6 on 17p13, with the most common fusion partner being MYH9 on 22q12. This leads to overexpression of USP6 under MYH9 promoter and appears to drive
tumorigenesis.40 These results suggest that nodular fasciitis may be an unusual phenomenon of transient or self-resolving neoplasia.39
tumorigenesis.40 These results suggest that nodular fasciitis may be an unusual phenomenon of transient or self-resolving neoplasia.39
Clinical Characteristics
The clinical presentation of nodular fasciitis is usually a firm, smooth, mobile subcutaneous nodule that grows rapidly over weeks to several months (Figure 97.1). Lesions are skin colored to light brown and measure 1 to 2 cm in diameter, but they can be up to 4 cm.41 When involving the upper eyelid, larger lesions can cause mechanical ptosis.1,17 In rare cases, NF can be immobile due to infiltration into the dermis and underlying muscle.19
Lesions may be painless and asymptomatic, but 55% are tender or even painful.34,36 One case was reported to have a cystic appearance that could be transilluminated.19 While most periorbital lesions involve the eyelid skin, rare cases have been described located beneath the episcleral conjunctiva (Figure 97.2).24,27 Periorbital NF lesions tend to be smaller than those in other parts of the body, possibly due to the less abundant subcutaneous fat and fascia.42
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