Musculoskeletal Medicine for Medical Students Disorders of the nail Author: Joseph Bernstein Version: 17 Date: 24-Mar-2014 15:09 Table of Contents 1 Description 4 2 Structure and function 5 38 3.1 Trauma 8 3.2 Infections 11 4 Malignant tumors 15 5 17 5.1 Nail manifestations of systemic disease 17 6 Clubbing is an increased curvature of the nail and nail fold in a proximal to distal direction, often with the appearance of a bulbous fingertip (Figure 9). The nail plate often has a shinny appearance. This is frequently a manifestation of systemic disease, with cardiac, pulmonary, and gastrointestional conditions being the most common, although it can occur without underlying etiology. The mechanism by which this occurs has not been clearly elucidated. 18 7 Red flags 20 7.1 Trauma 20 7.2 Infection 20 7.3 Tumor 20 8 Miscellany 21 9 Key terms 22 10 Skills and competencies 23 1 Description The fingernail serves multiple functions. In addition to protecting the fingertip, it provides tactile sensation, aids in thermoregulation, and assists in picking up small objects; it also has dense lymphatics in the hyponychium that help resist infection. The fingernail is the most frequently injured portion of the finger secondary to its prominent location. The nail is also susceptible to infection and may be the site of tumors, both benign and malignant. Last, the nail may display signs of underlying systemic disease. Version 17 4 Disorders of the nail 2 Structure and function The nail is a plate of keratin that covers the dorsal aspect of the distal phalanges of the fingers and toes. The anatomy of the nail is shown in figures 1 and 2. Version 17 5 Disorders of the nail (modified from http://www.aafp.org/afp/2008/0201/afp20080201p339-f1.gif and wikipedia, respectively) The nail plate (which, in layman’s terms, is the “nail” itself) is a hard sheet of translucent keratin in which lie several layers of dead, compacted cells. Disorders of the nail Version 17 6 The nail bed is the tissue that lies beneath the nail plate. The nail bed contains nerves, lymphatics and capillaries. (These capillaries are used to assess “capillary refill” by compressing the nail to momentarily occlude them, and then releasing the pressure to allow them to “refill”.) Within the nail bed is the germinal matrix, the source of cells that become the nail plate. As these cells are produced, older cells are pushed forward and compressed, giving rise to the typical growing pattern of the nail. A small piece of the matrix, the lunula (so named because it is white and crescentshaped, like a “little moon”) is often visible at the proximal most aspect of the nail. The eponychium is a small band of epithelium that covers the proximal aspect of the nail; the paronychium is a similar border tissue around the medial and lateral borders. The cuticle is a layer of epidermis that folds back over the surface of the nail plate at its base. Disorders of the nail Version 17 7 3 3.1 Trauma Trauma to the nails is common, with the middle finger being most commonly affected due to its length and greater exposure compared to adjacent shorter digits. There are often associated fractures of the distal phalanx. Mild trauma may result in a painful subungual hematoma: a collection of blood compressed between the nail plate and the nail bed on the distal phalanx. (Figures 3a). Figure 3a Treatment involves placing a hole in the nail plate to relieve the pressure, as shown in the figure (replace with photo?) Disorders of the nail Version 17 8 If the subungual hematoma involves more than 50% of the nail, the nail plate is generally removed and the nail bed repaired with fine absorbable sutures (Figure 3c). Figure 3c Nailbed lacerations are often the result of crush injuries, producing a stellate laceration pattern. These injures require repair. Without adequate repair (and some times despite best efforts) a cosmetic defect results. Malformations after healing can also be painful. Because nailbed lacerations are typically crush injuries, x-rays should always be obtained to exclude a fracture. Version 17 9 Disorders of the nail In children, it may be possible to repair the nailbed with a cyanoacrylate adhesive (eg, "Dermabond") with a cosmetic outcome comparable to that of suture repair. This option is advantageous in the pediatric population specifically because it avoids keeping the child motionless and is relatively pain-free. A hook nail deformity is a condition that results following amputation of the soft tissues and the tuft of the distal phalanx (Figures 4a-b}. The nail bed has lost the distal support and the nail grows downward around the tip of the finger. This is prevented by avoiding sutures in the distal nail bed and ensuring adequate bony support for the nail bed following traumatic injuries. Figure 4a Figure 4b Version 17 10 Disorders of the nail 3.2 Infections The nail is a site for both acute and chronic infections. Acute infections often result from a minor event, such as a superficial laceration or pulling a hangnail, with bacteria — typically Staphylococcus and Streptococcus — being the most common etiology. Chronic infections are typically fungal and may result from multiple acute infections treated with antibiotics or chronic moisture, with Candida being the most common etiology. Less commonly, atypical organisms, such as Mycobacterium, are the source of infection. These atypical infections are usually encountered in the setting of immunocomprised states. Paronychia (a collection of pus between the nail plate and the nail fold) and felons (a purulent collection forms on the palmar surface of the distal phalanx) are discussed in detail in the chapter on hand infections Herpetic whitlow is a viral lesion caused by the Herpes simplex virus and involves the paronychium. Prior to use of gloves by dental and medical professionals, this was seen in workers around oral secretions. It is currently more commonly seen in children who suck their thumb or fingers or in adults following contact with infected genitals. Initially, this has the appearance of an acute bacterial infection, but clear vesicles will eventually develop, helping differentiate this from an acute infection. The process is self-limiting, and incision and drainage should be avoided as a subsequent bacterial infection may occur, prolonging the time for resolution and often requiring additional treatment. photo of Herpetic whitlow of the hand Onychomycosis (ie, fungal infection of the nail) occurs more in toenails than in fingernails, but can be found in the latter. Diabetes, vascular problems or immunocompromised states are risk factors. Nail fungus can cause three problems (in order of frequency): cosmetic deformity, pain, and systemic spread. Onychomycosis is difficult to treat; recurrences are common. Oral medications such as terbinafine do not uniformly clear the infection, and side effects as severe as liver damage may result. Antifungal lacquers (eg Penlac) can help clear up some nail fungal infections but require diligent use (with frequent debridement) for up to one year. Surgery or laser ablation may also be employed. photo of Onychomycosis hand Benign tumors Tumors of the nail bed, though relatively uncommon, require the physician to have a heightened sense of awareness when a patient presents with pain or a change in the appearance of the nail. The most common benign tumors associated with the nail complex are mucous cysts (ganglion cysts), pyogenic granuloma, verucca, glomus tumors, and benign melonychia. Version 17 11 Disorders of the nail Ganglion cysts, more commonly referred to as mucous cysts in this location, are the most common tumor affecting the nail bed (Figure X). They result from an arthritic spur, or osteophyte, of the distal interphalangeal joint (DIP) of the fingers (or interphalangeal (IP) joint of the thumbs). Depending on the location of the cyst, the nail may have ridging, grooving or curvature, and the cyst may involve the eponychial fold. Treatment should be directed at removal of the stalk of the cyst and the underlying spurs of the joint. Nail deformities often improve following removal of the cyst. Because the cyst originates in the joint (and communicates with it) rupture of the cyst through the skin may introduce bacteria into the joint space Figure X. Ganglion (mucous) cyst JB: a photo showing this in PROFILE (showing elevation out of the plane of the photo) may be better Pyogenic granuloma is a raised lesion that is a proliferation of granulation tissue; it is frequently traumatized and bleeds. These lesions often develop when a wound has failed to heal and persistent bleeding prompts presentation to the physician. Like the Holy Roman Empire (which was said to be not Holy, Roman or imperial) pyogenic granuloma may be completely misnamed: "pyogenic" suggests infection, incorrectly; and there is no granuloma here either. Accordingly, the term Eruptive Hemangioma has been suggested. Most pyogenic granulomata resolve spontaneously. Those that do not can be removed with surgical excision or thermal ablation (eg electrocautery or freezing) Disorders of the nail Version 17 12 FIGURE X+1 (from wikipedia) Verruca vulgaris, or the common wart, may present around the perionychium. Multiple treatment methods are available, without any proving to be superior. When the eponychial fold is involved, permanent scarring may result. Glomus tumor is a neoplasm of the smooth muscle cells of the glomus body, which regulate blood flow and temperature in the finger (Figure 4). Half of these tumors occur in the subungual area (and give rise to nail deformities). As might be expected with any mass, glomus tumors can present with severe pain and point tenderness; the more specific finding is focal cold sensitivity. MRI with gadolinium is helpful for diagnosis; treatment involves excision of the mass. Figure X+2. Glomus tumor; image courtesy of Peter Murray, MD Disorders of the nail Version 17 13 Melonychia is a benign pigmented longitudinal streak in the nail bed (Figure 5). This can be concerning for melanoma, and microscopic tissue evaluation is necessary for the diagnosis. Biopsy is performed with a full thickness longitudinal incision following removal of the nail plate. The nail bed is undermined and closed with fine absorbable sutures. Figure X+3. Melonychia of the nail bed Version 17 14 Disorders of the nail 4 Malignant tumors Squamous cell carcinoma and melanoma are the most common malignancies of the nail complex. Radiographs of the finger should be obtained to evaluate for osseous changes of the distal phalanx. Squamous cell carcinoma is responsible for approximately 20% of all cutaneous malignancies, but is less common than melanoma in the subungual region. It may present with early skin changes or more advanced lesions (Figures 6a-b). Treatment typically involves amputation at the DIP joint of the finger (IP joint of the thumb). Figure xxa. Squamous cell carcinoma of the finger Figure xx-b. Squamous cell carcinoma of the thumb Malignant melanoma accounts for 4% of cutaneous malignancies, but is responsible for 80% of the deaths from cutaneous malignancies. Approximately 2% occur in the hand, and half of these are subungual. They may present as pigmented lesions in the nail bed or in the surrounding eponychium (Figures 7a-b). Full-thickness biopsy of the lesion is necessary to determine diagnosis and make treatment recommendations. Prognosis depends on the depth of invasion and sentinel lymph node status. Lesions greater than 1 mm in thickness or involving the entire depth of the nail bed should have sentinel lymph Disorders of the nail Version 17 15 node biopsy to evaluate for metastatic disease. Surgical treatment of the finger typically involves amputation proximal to the adjacent joint. Although Moh’s micrographic surgery has been performed in some cases, reconstruction is challenging, often resulting in worse functional outcomes than amputation. Figures 7a. Malignant melanoma of the thumb Figure 7b. Malignant melanoma of the finger Metastatic disease can occur to the fingertip, with lung primary being the most common primary source. About one third of the time, this is from an undiagnosed primary tumor and may mimic an infection. Disorders of the nail Version 17 16 5 5.1 Nail manifestations of systemic disease Version 17 17 Disorders of the nail 6 Clubbing is an increased curvature of the nail and nail fold in a proximal to distal direction, often with the appearance of a bulbous fingertip (Figure 9). The nail plate often has a shinny appearance. This is frequently a manifestation of systemic disease, with cardiac, pulmonary, and gastrointestional conditions being the most common, although it can occur without underlying etiology. The mechanism by which this occurs has not been clearly elucidated. Version 17 18 Disorders of the nail Figure 9. Clubbing of the fingers Version 17 19 Disorders of the nail 7 Red flags 7.1 Trauma crush injuries to the nailbed are associated with distal phalanx fractures subungal hematomas greater than 50% of the nail should be evacuated to relieve pressue 7.2 Infection fingernail infection with fungus may be a sign of diabetes, circulatory disorders a weakened immune system dysfunction. ruptured mucous cysts communicate with the joint space 7.3 Tumor Beware of melanoma! Disorders of the nail Version 17 20 8 Miscellany Patients of most vocations and avocations can perform functionally well following injury or amputation of a fingertip. In fact, an article entitled Less than ten - surgeons with amputated fingers in the Journal of Hand Surgery describes multiple physicians and surgeons who continue to practice following amputations of a digit. Fingernails grow approximately 2 inches per year Fingernails do NOT grow after death; rather, the surrounding skin retracts, giving that illusion Illicit drugs can be identified in nail clippings up to 8 months after last usage (and unlike hair test, which can be subverted by head-shaving, nail testing is much less likely to be undermined by completely removing the nail). The first syllable in the word “hangnail” does not refer to the nail “hanging” from the finger; rather, it’s root is ang, meaning pain (similar to the word “anguish”) Disorders of the nail Version 17 21 9 Key terms Fingernail, fingertip, perionychium, nail bed, subungual, mucous cyst, glomus tumor Version 17 22 Disorders of the nail 10 Skills and competencies Recognize both traumatic and acquired conditions affecting the nail and perionychium and have an understanding of treatment principles Version 17 23 Disorders of the nail