Nodular fasciitis is a lesion that typically presents in the subcutaneous tissue of adults in the third to fifth decade of life. It most commonly occurs in the upper extremities but can also arise in the head and neck and trunk, among other areas. Because nodular fasciitis can rapidly enlarge over the course of weeks, patients and their physicians can become quite concerned about an aggressive neoplasm, prompting biopsy. Over time, the growth of these tumors typically plateaus and they reach a size of no more than 3 cm in greatest dimension [2–4].

Fibromas of the tendon sheath arise in adult patients between the third and fifth decades of life and typically measure less than 2 cm in size [1, 8]. They present as slow-growing nodules that are attached to the tendons of the hands or feet. The thumb, index, and middle finger are the digits most commonly involved, and some patients can experience tenderness or limited range of motion in the involved digit [9, 10]. Given the location, these are often clinically presumed to be ganglion cysts [11].

Nuchal-type fibromas often arise as subcutaneous masses in adults around the head and neck area. Most measure 1–6 cm in greatest dimension [1]. Despite the designation as “nuchal,” approximately a third of these lesions will occur at other anatomic sites. Curiously, many patients (approximately 44%) with nuchal-type fibroma also have diabetes mellitus [13].

Gardner-associated fibromas occur in young children and are associated with familial adenomatous polyposis . A timely diagnosis can result in appropriate screening and prevention of future intestinal adenocarcinoma. It often arises as a subcutaneous lesion on the back or head and neck region [15]. In addition to fibromas and intestinal polyposis, patients with Gardner syndrome also present with epidermal inclusion cysts , osteomas , and deep fibromatosis (desmoid tumors) [16].

Elastofibroma is a benign fibrous proliferation that usually occurs beneath the muscles around the scapula or chest wall. This lesion predominantly manifests in older adults in the 6th to 7th decade. It is more common in females, and approximately half of patients have bilateral lesions [10, 18].

Superficial fibromatosis is a benign proliferation of fibroblasts that can occur in the hand (palmar fibromatosis), foot (plantar fibromatosis), or penis (penile fibromatosis /Peyronie disease ). Palmar fibromatosis predominantly occurs in Caucasian men over 65 years. These lesions arise slowly and evolve to the point of causing flexion contractures [1]. Plantar fibromatosis has a broader age distribution and can be found in young adults [19]. Both have been associated with numerous medical conditions such as type I and II diabetes mellitus and alcoholism [20, 21].

Deep or desmoid-type fibromatosis is a fibrous proliferation thought to arise from the connective tissue of muscle, overlying fascia, or aponeurosis. Conceptually, these tumors are divided into tumors that arise in the abdominal wall (abdominal fibromatosis ), within the abdomen (intra-abdominal fibromatosis ), or outside the abdomen (extra-abdominal fibromatosis ). Abdominal fibromatosis is usually seen in young women after childbirth [22]. Extra-abdominal fibromatosis often occurs in young adults (median age of 37 years) and arises in the shoulder, spine, thorax, hip, or thigh [23]. Intra-abdominal fibromatosis also occurs in young adults (average age of 41 years). A small subset of these arises as a manifestation of Gardner syndrome , a familial condition that includes deep fibromatosis, Gardner-associated fibroma, and familial adenomatous polyposis [24].

Solitary fibrous tumor is a fibroblastic neoplasm that can arise in multiple locations, including the extremities, pelvis, retroperitoneum, pleura, chest wall, and abdominal serosa. These tumors arise in patients of all ages with most extrathoracic lesions occurring in the sixth decade [27]. Rarely, these tumors can induce hypoglycemia , sweating, or even coma by secretion of insulin growth factor [28].