Benign tumors of the hand may be categorized using the different anatomic subunits of the hand. Each subunit has potential for disease processes and abnormal growth. Notably, the musculoskeletal, vascular, osseous, perionychial, cutaneous, and soft tissue elements can develop benign lesions that may manifest as localized masses of the hand.
Excluding cutaneous malignancy, 95% of tumors of the hand are benign. The nonneoplastic ganglion is probably the most common mass found on the hand and wrist. Some benign growths may not need excision.  Following ganglions, inclusion cysts, warts, giant cell tumors, granulomas, and hemangiomas follow in frequency. This article outlines each of the subunits, discusses benign growths that may exist in each anatomic structure, and serves as an introduction to this broad topic.
A study by Sluijmer et al involving patients of three hand surgeons indicated that the following factors make surgical management of benign upper extremity tumors significantly more likely  :
Greater number of pretreatment visits
Presence of giant cell tumors
Presence of lipomas
Presence of tumor on the finger
Prior occurrence of upper extremity tumors
The patient’s choice of hand surgeon was also found to influence the probability of surgery. The study included records on 1593 tumors.
Classification of Musculoskeletal Tumors
Benign tumors are classified as having 3 stages.  First are latent stage I tumors, which do not need excision. These lesions resolve spontaneously or remain unchanged. Active stage II benign neoplasms grow within a limited zone and are contained by natural barriers. Excision and treatment usually involves a marginal or intralesional procedure such as curettage.  Locally aggressive stage III benign tumors extend beyond natural borders and often require en bloc resection for cure. 
Mulliken and Glowacki defined hemangiomas as true tumors seen in the first 4 weeks of life.  Although 30% are seen at birth, 70-90% are visible by the fourth week of life.  The rapid growth phase lasts approximately 10-12 months.  During this time, the mass may develop from a reddish-purple lesion to a large, bright-red or bright-blue mass.  During the third, or last, phase, the lesion involutes. By age 7 years, 70% of lesions have involuted.  Hemangiomas occur 3 times more frequently in females than in males.  Lesions that do not involute are labeled capillary or cavernous based on histologic criteria.  Noninvoluting capillary hemangiomas are termed port-wine stains or nevusflammeus.  Noninvoluting cavernous hemangiomas have arteriovenous flow that may be categorized as either high or low, ie, high- or low-flow state. 
Plain radiographs demonstrate that hemangiomas have a soft tissue shadow and may contain calcifications.  Typically, hemangiomas have well-defined borders on CT scan images.  With the increased use of MRI, the reliance on angiography has diminished. 
Management of hemangiomas is usually conservative because most involute spontaneously by age 7 years.  Treatment of hemangiomas focuses on their inherent complications, such as bleeding, infection, and ulceration. Kasabach-Merritt syndrome has been associated with hemangiomas. This syndrome involves diffuse coagulopathy secondary to platelet trapping within the hemangioma. With repeated infections and ulcerations, surgical management may be necessary. Treatment of the lesion should include ligation of the feeding vessels and complete excision. YAG laser ablation has also been used.  The prognosis and recurrence rate associated with hemangiomas is related to the size and degree of soft tissue involvement. Diffuse lesions are reported to be associated with a higher recurrence rate. 
Glomus tumors are benign lesions containing cells of a glomus apparatus. The glomus body lies in the reticular layer responsible for thermoregulatory control.  The glomus apparatus contains an afferent vessel, a Sucquet-Hoyer canal, and multiple shunts in the glabrous skin of the hand and beneath the nail beds.  Numerous nonmyelinated nerve fibers are seen histologically.  The classic triad observed with glomus tumors is cold hypersensitivity, paroxysmal pain, and pinpoint pain.  The pain caused by glomus tumors is not primarily nocturnal, has a paroxysmal pattern, and is not usually relieved with salicylates. 
Physical findings of a glomus tumor include painful subcutaneous nodules in the subungual region.  As many as 75% of glomus tumors are found in the hand, and up to 65% of these lesions are found in the fingertip.  The pain associated with glomus tumors may be elicited by light touch or cold exposure.  Bluish discoloration in the nail beds, with or without nail plate ridges, may be associated with the presence of a glomus tumor. 
Imaging of glomus tumors includes MRI, which delineates a dark, well-defined lesion on T1-weighted images and a bright lesion on T2-weighted images.  Doppler ultrasound studies can also be used to help detect the high blood flow that occurs in glomus tumors. Glomus tumors are classified into 3 groups: solitary lesions, multiple painful lesions, and multiple painless lesions. 
Treatment of glomus tumors is excision. Following removal of the nail, the nail bed is exposed. Careful examination of the matrix is necessary because recurrence rates reportedly are as high as 20%.  Persistence of symptoms following exploration may require reexploration secondary to the likelihood of multiple lesions.
A study by Harrison et al indicated that an association may exist between glomus tumors of the hand and neurofibromatosis. The investigators determined that out of 21 patients with glomus hand tumors, six (29%) had been diagnosed with neurofibromatosis, while in a control group of 200 patients with excised ganglion cysts, no neurofibromatosis had been found. The study reported that compared with the control group, the odds ratio that neurofibromatosis would be diagnosed in association with a glomus tumor was 168:1, suggesting that glomus tumors should be considered when painful hand or finger lesions occur in patients with neurofibromatosis. 
Enchondromas, which arise from cartilage, are the most common primary bone tumors.  Enchondromas account for more than 90% of bone tumors seen in the hand.  The proximal phalanx is the most common site of occurrence, with lesions also occurring in the metacarpal region. Radiographically, an enchondroma is usually seen as a well-defined radiolucent lesion in the diaphysis or metadiaphysis.  These lesions may also have a well-defined sclerotic rim. The cortex may have small concavities or may be scalloped in appearance.  Ollier disease is a condition of multiple enchondromas.
Subperiosteal osteoid osteomas have been reported in the literature and can cause pain and swelling.  Osteoid osteomas are benign lesions that cause a core in the bone and pain in younger patients. Of all bone tumors, 10-12% are osteoid osteomas.  These lesions primarily occur in children and young adults. 
The pathologic features are an avascular central portion surrounded by sclerotic bone.  Osteoid osteomas occur primarily in the cortex or metaphysis of long bones.  However, reportedly, 50% of all osteoid osteomas occur in the intra-articular or juxta-articular region of the femur and tibia.  The classic presentation of osteoid osteoma includes a nocturnal occurrence of pain, localized pain with or without swelling, and referral of pain to an adjacent joint. 
Treatment of osteoid osteomas entails excision and drainage. These lesions have an elevated prostaglandin level; therefore, anti-inflammatory medications decrease pain in most situations.  Excision of the nidus of the osteoid osteoma is curative, but the lesion may recur if the inciting vascular nidus is not completely removed. [14, 15]
Osteoblastoma is an uncommon bone tumor of the hand sometimes mistaken for an osteoid osteoma.  These lesions may appear histologically similar. However, benign osteoblastomas can be distinguished from osteoid osteomas by their higher growth potential and lack of associated nocturnal pain. 
Giant cell tumors
Giant cell tumors of the hand are most frequently found in patients aged 20-40 years.  Jaffe provided the clinical description and grading system used today.  Pain is frequently the primary symptom.  The prevalence rate of pathologic fracture is approximately 6%.  For the wrist and hand, the distal radius is affected most commonly.  Giant cell tumors have also been reported in the middle phalanx. 
Surgical options include arthroplasty or arthrodesis for reconstruction of larger defects.  In the past, intralesional curettage was associated with a significant rate of recurrence.  Currently, the use of adjuvants (eg, cryosurgery, bone cement packing) has decreased the rate of recurrence following intralesional curettage.  With the use of these adjuvants, the rate of recurrence has decreased to below 10%.  However, others still believe that the rate of local recurrence remains despite the use of bone grafting.  Others have performed arthrodesis of the wrist following giant cell tumor resection, using a vascularized fibular flap for large lesions. 
Additional benign bone tumors occurring elsewhere in the body include enchondroma, osteochondroma, chondroblastoma, and chondromyxoid fibroma. 
Aneurysmal bone cyst
Aneurysmal bone cysts account for about 5% of benign bone tumors, and those occurring in the hand account for approximately 3-5% of all aneurysmal bone tumors. The peak incidence of hand cases occurs in the second decade. These lesions present with pain and rapid growth, especially during pregnancy. They mostly occur in the metacarpal bones, followed by the phalangeal bones and, rarely, the carpal bones. Radiographically, they may resemble giant cell tumor of bone, having soap-bubble appearance with no calcification.
These lesions are lytic, eccentric, expansile lesions with sharp boundaries but no marginal sclerosis. Curettage and bone grafting are the historic treatment modalities; curettage alone is associated with high recurrence rates, and total excision of the lesion may result in loss of function. [24, 25] Adjuvant treatment modalities such as cryosurgery or electric cauterization may usually be considered with curettage, and total excision should be preserved for the recurrent cases. [26, 27, 24, 28]
Unicameral bone cyst
Unicameral bone cysts are benign cystic lesions of uncertain etiology that usually arise in the metaphysis of long bones. These lesions appear in childhood and usually affect males twice as commonly as females in the first 2 decades of life.  Their most common location is the proximal humerus. These lesions are usually asymptomatic and present late by pathological fractures. 
Radiographically, unicameral bone cysts are lytic metaphyseal lesions with well defined borders and septae or minor trabeculation.  Treatment is usually indicated to prevent pathological fractures and deformities.  Treatment includes observation; injection of corticosteroids; curettage plus bone grafting; a combination injection of corticosteroids (steroids), demineralized bone matrix, and bone marrow aspirate (SDB); drilling; or en bloc excision.  In a study on 167 patients with unicameral bone cysts, Sung et al concluded that the combination SDB injection was a reasonable first treatment in the humerus and femur, as it is less invasive than curettage but comparable in preventing recurrence.  Cyst aspiration and corticosteroid injection is becoming a more popular treatment because of the low risk of complications. 
Schwannoma or neurilemmoma
The most common solitary tumor of peripheral nerves is the schwannoma or neurilemmoma. Peripheral nerve tumors account for fewer than 5% of all tumors of the hand.  Usually, schwannomas manifest as asymptomatic swellings along the course of a peripheral nerve. Typically, no sensory or motor deficits are noted in these nerves.  Treatment is enucleation of the tumor without disruption of the integrity of the nerve fasciculi. 
Fibrolipomatous hamartoma of the neural structures of the hand is a rare lesion.  These lesions are described to occur most commonly in the median nerve. However, these lesions have also been observed in the radial, ulnar, digital, superficial peroneal, plantar, and cranial nerves.  Larger masses may cause numbness or weakness of the digits.  These findings are similar to those found in persons with carpal tunnel syndrome.  These particular lesions are characterized by fibrofatty proliferation causing epineural and perineural fibrosis.
Images from MRI studies demonstrate that these lesions appear similar to a coaxial cable in the axial plane and similar to spaghetti in the coronal plane.  These patients typically present when younger than 30 years.  Of all persons with this tumor, 30-66% exhibit macrodactyly due to the bony overgrowth and progression of subcutaneous fat. 
Neurofibromas are sometimes referred to as hamartomas because of the theory that these lesions represent malformations of nerve tissue and are not true tumors.  Solitary neurofibromas occur most frequently in the first decade of life.  Symptoms may include associated pain and varying degrees of peripheral dysfunction secondary to the growth of the neurofibroma.  Multiple neurofibromas may be associated with von Recklinghausen disease.
Surgical removal of these lesions may be reserved for symptomatic pain or paralysis due to the effects of the neurofibroma on normal nerve fibers.  Following resection of neurofibromas, nerve grafting may be necessary to restore function. 
In a recent review by Lincoski et al, a single hand surgeon's pathology reports were reviewed over a 16-yr period.  The authors state that 11.5% of 208 soft-tissue tumors were benign nerve tumors. Of all lesions, giant cell tumors were most common, followed by inclusion cysts and nerve tumors.
Mucous cysts are ganglion cysts that occur on the dorsum of the distal phalanges and emanate from the distal interphalangeal joint.  First described by Hyde, these lesions occur most frequently in persons aged 40-70 years and primarily in women rather than men.  Reportedly, mucous cysts occur more commonly in the index and long fingers.  Osteoarthritic changes in the distal interphalangeal joint are common. 
Although these lesions may be self-limiting, they are treated when the overlying skin thins, when pain occurs, when drainage appears at the nail fold, or when significant trophic fingernail changes are noted. Appropriate treatment is performed with skin elevation via a skin flap, elevation of the terminal extensor tendon apparatus, and debridement of the dorsal aspect of the distal interphalangeal joints at the point where the cyst originates. Osteophytes are commonly removed. The skin flap may need to be advanced distally for coverage of the joint. Treatment aimed at the cyst is often unnecessary.
Nodular fasciitis has been described as a rapidly growing tumor of the hand.  Histologically, this lesion is a benign reactive fibroblastic lesion in the subcutaneous tissue that is known for rapid growth.  Originally, this lesion was termed subcutaneous pseudosarcomatous fibromatosis.  Its pathogenesis may be related to a local reactive or inflammatory process.
Males and females are equally affected.  Nearly half of these patients have pressure or pain.  These lesions occur most frequently on the flexor surface of the forearm.  Typically, nodular fasciitis may manifest as a round or oval nodule that may or may not be encapsulated.  Histologically, these nodules are composed of immature fibroblasts in short, irregular bundles.  The differential diagnosis includes fibrosarcoma, which is similar in histologic appearance. Nodular fasciitis usually follows a benign course and is readily treated with local excision. 
A pyogenic granuloma may occur in the skin as a solitary tumor.  Clinically, it may appear as a reddish nodule that may ulcerate.  Frequently, this lesion is seen on the upper limbs and especially the hand. Traditionally, its etiology is variable. Trauma is considered one possible cause of these lesions. A popular belief is that these lesions occur in response to a traumatic event in which a localized infection develops.  In the absence of trauma in certain cases, vascular causes have also been cited.  Attempt to distinguish these lesions from amelanotic melanomas; pyogenic granulomas may develop hemosiderin deposits and may become brown in appearance. 
Definitive treatment of pyogenic granulomas includes excision with a generous margin of surrounding normal tissue. An alternative treatment is to shave off the lesion flush with the skin and coagulate the base. Care must be taken to not damage underlying structures. Treatment with shaving and coagulation is often effective. Early recurrences can be treated with repeat shaving and coagulation.
Soft Tissue Lesions
Ganglions are the most common soft tissue tumors of the hand.  These common lesions are usually found on the dorsum of the wrist, followed by the volar wrist, flexor tendon sheath, and dorsal distal interphalangeal joint (the mucous cyst). When ganglions occur on the volar surface of the distal interphalangeal joint, they may be confused with a felon of the fingertip. They are defined as cystic swellings that are closely connected to joint or tendon sheaths and contain mucinous material.
Ganglion cysts are pseudocysts and do not contain an epithelial lining. As such, the focus of treatment is the site of production or leakage of this fluid rather than the cyst itself. When the cysts are aspirated or punctured, the sudden decrease in cyst pressure may allow the 2 sides of the stalk to coapt and close. Excision of the stalk and debridement of the dorsal aspect of the scapholunate ligament is thought to be the most important aspect in achieving a low recurrence rate from excision of the common dorsal wrist ganglion.
One study evaluated the surgical treatment results of symptomatic ganglion cysts in pediatric patients. The results found that complete surgical removal is effective in pediatric patients, with low rates of recurrence. 
Volar wrist ganglions emanate from the radioscaphocapitate ligament at the site of the radioscaphoid joint. These ganglions typically form part of their wall with the radial artery and veins. Excision requires complete dissection and protection of the radial artery and a preoperative assessment of the importance of the radial artery to hand blood flow.
Lipomas are one of the most common tumors of the body. Notably, the growth of lipomas in the hand may cause neurologic changes in the peripheral nerves of the hand. Compression of the median nerve causes a syndrome similar to carpal tunnel syndrome. Symptoms may include thenar weakness; atrophy; and sensory deficits of the thumb, index finger, and long fingers.  Compression of the lateral cutaneous nerve of the forearm by a lipoma may cause pain to radiate to the dorsum of the thumb.  Sensory deficits of the dorsum of the thumb, index finger, and long fingers can be caused by compression of the superficial radial nerve. Finally, sensory deficits of the fourth and fifth fingers may result from ulnar nerve compression by a lipoma. 
Localized nodular tenosynovitis is otherwise known as giant cell tumor of the tendon sheath. These lesions are noted for their high recurrence rates.  These lesions occur most frequently at the synovial sites of the hand, including the joints, capsular ligaments, and tendon sheaths.  Localized nodular tenosynovitis has been found to occur more frequently in the index and long fingers.  The palmar surfaces of the hand are more commonly involved. 
The reported recurrence rate for these lesions is 9%.  Histologically, these lesions contain collagenized stroma, hemosiderin pigment, giant cells, and histiocytes.  Optimal treatment includes a thorough search for the capsular or deep attachments and wide exposure.  The synovial origin of these lesions prompts such an extensive search for deeper attachments to the lesion. 
In a recent report by Fu et al, a leiomyosarcoma of the cephalic vein was described.  The report states that leiomyosarcomas of veins develop 5 times more frequently in veins than in arteries. 
Importantly, recognize systemic processes that cause benign lesions of the hand. These can include gout, rheumatoid arthritis, and xanthomatosis from hypercholesterolemia. Additional tumors of the hand include carpometacarpal bossing, anomalous extensor manus brevis muscle, or extensor tenosynovitis. Subungual melanomas may only be distinguished from subungual hematomas with a biopsy specimen examination. Keratoacanthomas are rapidly expanding and changing skin lesions with a central keratin plug that superficially appears volcanolike. Histologically, these benign skin lesions, which eventually regress, may be confused with squamous cell carcinomas.