Dermatology

Piezogenic Pedal Papules (Painful piezogenic pedal papules, piezogenic wrist papules)

Synonyms: Painful piezogenic pedal papules, piezogenic wrist papules

Are You Confident of the Diagnosis?

What you should be alert for in the history

First described by Shelley and Rawnsley in 1968, piezogenic pedal papules are flesh-colored papules which emerge on the heel upon weight bearing. Herniations of subcutaneous fat give rise to these papules. Upon cessation of weight bearing, the papules frequently recede and vanish. Characteristically, the patient presents with a history of multiple painless papules on the heel bilaterally. In rare cases, piezogenic pedal papules are painful. In point of fact, 7.1% of the 466 cases reported in the literature were painful.

The pain associated with piezogenic papules is sharp, lancing, and focal. Painful piezogenic pedal papules have also been associated with concomitant tibialis anterior muscle herniation.

Be alert for flesh-colored papules extending to the anterior surface of the shins.

An analogous condition of the wrist also exists, termed piezogenic wrist papules. To date, painful piezogenic wrist papules have not been reported.

Characteristic findings on physical examination

Piezogenic papules are soft, compressible, flesh-colored papules that appear and become firm or tense when the patient stands and bears weight (Figure 1). Characteristically, multiple papules are present bilaterally, ranging in size from 0.2 to 1 cm in diameter. In most cases, 2-4 papules are present, however, up to 18 papules have been observed on a single foot. These papules predominate on the medial aspect of the heel, although papules on the posterior and lateral heel are not uncommon.

Figure 1.

Piezogenic pedal papules.

Infantile pedal papules have a tendency to be more nodular and predominate on the medial plantar aspect of the foot. A rare case of piezogenic papules on the medial longitudinal arch in adults has also been reported.

Piezogenic wrist papules are elicited by applying pressure to the heel of both palms with the arms internally rotated and flexed at 90 degrees and the wrists extended at 90 degrees. During this maneuver, the papules appear on the volar surface of the wrist.

Expected results of diagnostic studies

Histopathology

A hyperkeratotic stratum corneum and acanthotic epidermis are observed, consistent with an acral site. At the dermal-subcutaneous junction, connective tissue trabeculae are thinned or absent and compartmentalization of subcutaneous fat is lost.

Subcutaneous adipose tissue can be seen protruding into a dermis containing fragmented elastic fibers.

A nonspecific degeneration of collagen and hyaline thickening of dermal vessels has also been reported.

The aforementioned findings are more consistent with painful piezogenic papules. Biopsies of painless piezogenic papules may not reveal any histologic abnormalities.

Diagnosis confirmation

Differential diagnosis

Rheumatoid nodules (firm nodules usually on the extensor extremities)

Calcaneal spurs

Plantar fasciitis

Calcaneal stress fracture

Tarsal tunnel syndrome

Achilles tendon enthesitis

Rheumatoid nodules are flesh-colored nodules which may be painful if present on the sole or heel. Like piezogenic papules, they may be singular or multiple and range in size from millimeters to centimeters. Although rheumatoid nodules tend to be slightly larger than piezogenic papules, the two entities are most readily differentiated on the basis of the lesion’s consistency. Rheumatoid nodules are hard with a bonelike consistency, while piezogenic papules are characteristically soft. The presence of concomitant arthritis, arthralgia, and systemic symptoms also favors a diagnosis of a rheumatoid nodule.

In light of expanded prevalence data published in recent years, piezogenic papules are now thought to be a normal variant. Thus, in the setting of diffuse foot pain and concomitant piezogenic papules, other etiologies for the pain should be considered including tarsal tunnel syndrome, peripheral enthesitis, calcaneal fractures, and calcaneal spurs.

Calcaneal spurs frequently manifest with foot pain and overlying hypercallosities. These calluses are easily distinguished from the piezogenic papule on the basis of appearance alone, but regardless of their presence or absence, the heel should be palpated in an effort to identify bony prominences. An X-ray may be useful if the diagnosis is unclear.

Heel pain following a solitary traumatic event is almost certainly a calcaneal fracture. Such a fracture will be visible on X-ray. In contrast, a stress fracture is caused by repetitive minor trauma or stress and may not appear on routine X-ray. If the diagnosis is suspected, consider magnetic resonance imaging (MRI).

The insertion sites for the plantar fascia and Achilles tendon on the calcaneous are common sites of peripheral enthesitis. Patients with plantar fasciitis characteristically report pain upon getting out of bed in the morning or after prolonged periods of nonweightbearing. The pain associated with plantar fasciitis can be reproduced with palpation of the either the medial tubercle of the calcaneous or the proximal aspect of the plantar fascia. Passive dorsiflexion of the toes or standing and walking on the toes may also reproduce the pain. Peripheral enthesitis is frequently observed with the spondyloarthropathies.

Consider this diagnosis in the setting of concomitant back pain, arthritis, arthropathy, morning stiffness, fever, weight loss, and fatigue. Palpate other sites of enthesitis commonly involved including the base of the fifth metatarsal head, the tibial tuberosity, the superior and inferior poles of the patella, and the iliac crest.

Tarsal tunnel syndrome is characterized by pain, burning, tingling, and numbness on the medial aspect of the ankle, midfoot, and sole. Atrophy of the foot musculature may be present. Eversion and dorsiflexion exacerbates symptoms, particularly at the endpoint range of motion. Percussion of the posterior tibial nerve posterior to the medial malleolus produces distal parasthesias.

Who is at Risk for Developing this Disease?

Significant interstudy variability exists among those studies examining the prevalence of piezogenic papules. When all studies are considered, prevalence ranges from 2.4% to 100%.

The true prevalence is likely in the 75-85% range, consistent with the most recent published data. Painless piezogenic papules should be considered a normal finding or normal variant. They occur in all age groups and in both males and females, although they are reported more often in women than in men.

Cases in the same family have been described, however, given the almost universal prevalence of the condition, it is unlikely that these papules are hereditary. In most cases, painless piezogenic papules are not the result of an inherent connective tissue defect.

Painful piezogenic papules are indeed a rare occurrence. Among the 466 cases of piezogenic pedal papules reported in the literature, 7.1% were painful.

Because they are primarily seen in adult patients, they may result from the cumulative effect of many years of repetitive pressure on the heels in susceptible patients. This theory is analogous to the formation of abdominal hernias. Obesity, rigorous athletic activity, prolonged weight bearing, being flat-footed, and Ehlers-Danlos syndrome are postulated risk factors. Indeed, in a case series of 29 patients with Ehlers-Danlos syndrome, 10/29 presented with painful piezogenic papules.

In another case series of 23 subjects with sports involvement and piezogenic pedal papules. 12/23 complained of pain. These painful papules also occur in individuals with no apparent risk factors.

In the pediatric population, reports of painful piezogenic papules are limited to a single case of a 5-year-old child with Ehlers-Danlos syndrome. Thus far, painful piezogenic papules have not been reported in healthy children. Infantile pedal papules are seen in 6% of neonates and 40% of infants.

In a study of 322 healthy children aged 4 to 13, 72% had one or more piezogenic pedal papule.

What is the Cause of the Disease?

Etiology

Pathophysiology

Piezogenic papules arise from the herniation of subcutaneous fat into the dermis through connective tissue defects. Painless papules represent the small, peripheral fat chambers seen in a normal heel.

Painful papules result from degeneration of separating trabeculae and fusion of peripheral fat chambers.

The result is a larger defect more likely to contain associated neurovascular structures. The pain associated with piezogenic papules is a consequence of ischemia and nerve entrapment.

Systemic Implications and Complications

It is proposed that painful piezogenic papules are a consequence of either a latent inherited or an acquired structural defect of the connective tissue. Although the painful piezogenic papule is a relatively benign condition, it is important to be cognizant of its existence because it may be the first clinical sign of a latent connective tissue disease. It is imperative to obtain a thorough history and physical, searching for evidence that would support a diagnosis of Ehlers-Danlos syndrome.

Although six distinct phenotypes exist, shared clinical features include skin hyperextensibility, joint hypermobility and excessive dislocations, tissue fragility, poor wound healing, wide atrophic scars known as “cigarette paper scars,” and easy bruising. If any of these signs or symptoms are present, the patient should be referred to a geneticist for diagnostic confirmation, subtype determination, and appropriate genetic counseling.

Painful piezogenic papules can limit ambulation and exercise. Short-term sequelae include general deconditioning and deep vein thrombosis. If untreated, possible long-term sequelae include obesity, hypertension, hyperlipidemia, diabetes mellitus, and cardiovascular disease.

Treatment Options

Treatment options are summarized in Table I.

Table I.

Treatment options for piezogenic pedal papules
 Medical Steroid/Anesthetic injection
 Physical modalities                  Fitted heel cups
  Foam rubber foot soles
  Compression stockings
  Tape
  Orthotic devices
  Electro-acupuncture
   
Surgical treatment Deep punch biopsy excision with closure of fascial defect

Optimal Therapeutic Approach for this Disease

Painless piezogenic papules are common, asymptomatic, and without risk of complication. No treatment is necessary.

Painful piezogenic papules cause suffering and limit ambulation. The condition should be treated after other etiologies for foot pain have been ruled out. Published data pertaining to the treatment of piezogenic pedal papules are limited to case reports and small case series. Only tentative conclusions regarding the most effective therapy can be made.

As a result, we recommed initiating treatment with conservative measures and progressing to move invasive procedures. For conservative measures to be effective, undue pressure to the foot must be eliminated. Prolonged periods of standing and repetitive trauma to the foot should be avoided at all costs. The case report literature supports the use of compression stockings, fitted heel cups, foam rubber foot soles, taping of the heel, and orthotic devices.

If conservative measures fail, the preferred modality is an injection of a steroid and local anesthetic mixture. Injection of 1-2mL of 1:1 betamethasone and bupivacaine resulted in a 50% reduction in pain after a single injection. After a second injection at 1 month, pain scores had decreased to 20%. The patient remained pain following a third injection at 2 months. If the patient continues to have pain, consider electro-acupuncture. A patient who failed conventional therapy and traditional acupuncture has been reported. After two weekly 15-minute sessions, the patient was pain free. The patient was maintained pain free on 15-minute treatment sessions every 2 weeks.

If the pain persists despite multiple conservative interventions, consider surgical treatment. Bear in mind that a significant proportion of the painful piezogenic pedal papules reported in the literature occur in patients with impaired wound healing secondary to Ehlers-Danlos syndrome. Surgery should be avoided in this patient population if at all possible. Even for the otherwise healthy patient, surgical intervention is the treatment of last resort. A deep punch biopsy with subsequent closure of the fascial defect is preferred over extensive excisional surgery.

Patient Management

The authors recommend a 2-4 week trial of conservative treatment before proceeding to injections. If the patient fails to respond to conservative measures and at least two monthly injections, consider a referral to podiatry to rule out other etiologies before proceeding with surgical revision.

Unusual Clinical Scenarios to Consider in Patient Management

Painful piezogenic pedal papules have also been associated with concomitant tibialis anterior muscle herniation. Be alert for flesh-colored papules extending to the anterior surface of the shins. Surgery should be a last resort for these lesions in patients with Ehlers-Danlos syndrome.

What is the Evidence?

Shelley, WB, Rawnsley, HM. "Painful feet due to herniation of fat". J Am Med Assoc. vol. 209. 1968. pp. 308-9.

(First published description of piezogenic pedal papules.)

Doukas, DJ, Holmes, J, Leonard, JA. "A nonsurgical approach to painful piezogenic pedal papules". Cutis. vol. 73. 2004. pp. 339-46.

(Case report describing successful treatment of painful piezogenic pedal papules with a betamethasone and bupivacaine injection.)

Woodrow, SL, Brereton-Smith, G, Handfield-Jones, S. "Painful piezogenic pedal papules: response to local electro-acupuncture". Br J Dermatol. vol. 136. 1997. pp. 628-30.

(Case report describing successful treatment of painful piezogenic pedal papules with electro-acupuncture.)

Pontious, J, Lasday, S, Mele, R. "Piezogenic pedal papules extending into the arch". J Am Podiatr Assoc. vol. 80. 1990. pp. 444-5.

(Case report presenting a unique case study of a painful piezogenic pedal papule on the medial longitudinal arch and its successful treatment with a soft foam rubber insole.)

Laing, VB, Fleischer, AB. "Piezogenic wrist papules: a common and asymptomatic finding". J Am Acad Dermatol. vol. 24. 1991. pp. 415-7.

(First published description of piezogenic wrist papules.)

Boni, R, Dummer, R. "Compression therapy in painful piezogenic pedal papules". Arch Dermatol. vol. 132. 1996. pp. 127-8.

(Case report describing successful treatment of painful piezogenic pedal papules with compression stockings.)

Kahana, M, Feinstein, A, Tabachnic, E, Schewach-Millet, M, Engelberg, S. "Painful piezogenic pedal papules in patients with Ehlers-Danlos Syndrome". J Am Acad Dermatol. vol. 17. 1987. pp. 205-9.

(A case series of 29 adult patients with Ehlers-Danlos syndrome. This study was the first to support the theory that connective tissue disease is a risk factor for painful piezogenic pedal papules.)

Kahana, M, Levy, A, Ronnen, M, Cohen, M, Schewach-Millet, M. "Painful piezogenic pedal papules on a child with Ehlers-Danlos Syndrome". Ped Dermatol. vol. 3. 1985. pp. 45-7.

(The first published report of painful piezogenic pedal papules in a child. This 5-year-old female also carried a diagnosis of Ehlers-Danlos syndrome.)

Schlappner, OL, Wood, MG, Gerstein, W, Gross, PR. "Painful and nonpainful piezogenic pedal papules". Arch Dermatol. vol. 106. 1972. pp. 729-33.

(A review of key histopathologic differences between painful and nonpainful piezogenic pedal papules.)
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