Acrokeratosis Paraneoplastica Bazex= تقران النهايات نظير السرطاني لبازيكس |
Acrokeratosis of
Bazex
EPIDEMIOLOGY
Bazex established an association between this uniquely distributed papulosquamous eruption and underlying malignancy. In fact, he considered the characteristic cutaneous presentation a pathognomonic sign of internal malignancy. There have been more than 100 cases reported in the medical literature. Patients are typically men over the age of 40 years old. Acrokeratosis paraneoplastica is unrelated to Bazex-Dupre-Christol, which is a genodermatosis characterized by congenital hypotrichosis, follicular atrophoderma, and basal cell carcinomas arising at an early age. ETIOLOGY AND PATHOGENESIS The mechanism by which this characteristic eruption occurs is still speculative. One theory proposes that antibodies mounted against the tumor cross-react with keratinocyte or basement membrane antigens (similar to those found in paraneoplastic bullous pemphigoid). Other theories include a T-cell mediated immune response to tumor-like antigens in the epidermis or excessive expression of autocrine growth factors from the tumor resulting in epidermal hyperplasia. CLINICAL FINDINGS The name, acrokeratosis paraneoplastica, is aptly descriptive because characteristic lesions are located acrally and exhibit hyperkeratosis. The plaques are usually erythematous to violaceous with overlying scale. Almost all patients have lesions affecting the ears and nails during the disease. Nearly two-thirds will demonstrate involvement of the nose and fingers, and over one-half have lesions on the hands and feet, especially volar surfaces. Other clinical findings include hyperpigmentation and bullae. Bullae, when present, are most common on the hands and feet. ACROKERATOSIS PARANEOPLASTICA OF BAZEX AT A GLANCE
Three stages of skin lesions parallel the growth and dissemination of the underlying tumor. In the first stage, the helices, nose, fingers, and toes are usually affected in a symmetric fashion. Early lesions are macular and not clearly demarcated, simulating a non-specific dermatitis. They may exhibit crust in addition to scale. The eruption is classically asymptomatic, but pruritus may be a problem. Paronychia is the first sign of nail involvement . In most cases, the responsible tumor is occult at this stage and remains so for an average of 11 months. During the second stage, the tumor exhibits symptoms, due to local extension or metastatic spread, and the skin eruption becomes more extensive. The cheeks display the typical red to purple scaly or crusted plaques. The palms and soles develop a keratoderma that often spares the central volar surfaces but may lead to painful fissures . Nail plate changes include yellowing, thickening, onycholysis, and ridging, both horizontal and vertical. The final stage is observed when the tumor goes untreated or fails to respond
The main differentiation to be made in diagnosis is psoriasis, especially acral variants. The distinguishing clinical feature, which is nearly always present in acrokeratosis paraneoplastica, is involvement of the helices of the ears and the tip of the nose. Knees and elbows may develop plaques but it occurs late in the disease. Typically, Bazex is treatment resistant unlike other diseases considered in the differential. Mucosal squamous cell carcinoma of the head and neck is the most frequently associated malignancy in acrokeratosis paraneoplastica and is markedly over-represented when compared with the cancer statistics in the general population. Tumors in the oropharynx or larynx and cervical squamous cell lymph node metastases of an occult primary malignancy make up more than 60 percent of cancers associated with Bazex syndrome but only 7 percent of cancer patients without Bazex. The lung and esophagus were the next most frequent site of tumors (15 percent and 10 percent, respectively), though not always squamous cell carcinomas. Histologically, some psoriasiform features are present, including hyperkeratosis, parakeratosis, and a superficial lymphohistiocytic infiltrate, but other nonpsoriasiform changes also exist. These include vacuolar degeneration with melanin-containing macrophages in the dermis and dyskeratotic keratinocytes.41 DIFFERENTIAL DIAGNOSIS (Box 154-1) COMPLICATIONS The keratoderma affecting volar surfaces may develop fissures. On the feet, this can lead to painful ambulation. Secondary infection occurs. Paronychia is usually painful and may be debilitating. Box 154-1 Differential Diagnosis of Acrokeratosis Paraneoplastica Most Likely
Consider
Always Rule Out
PROGNOSIS AND CLINICAL COURSE The skin eruption is expected to resolve with treatment of the underlying malignancy and can reappear with tumor recurrence. For some patients the cutaneous lesions, but more commonly the nail dystrophy (ridging and subungual hyperkeratosis), may persist despite (presumed) successful tumor eradication. TREATMENT Adequate treatment of the underlying malignancy usually results in improvement of acrokeratosis paraneoplastica and recurrence of the eruption heralds tumor recurrence. The skin lesions are typically resistant to standard therapies for hyperkeratotic conditions, and few treatments specific for the cutaneous component of acrokeratosis paraneoplastica have been reported. Retinoids have been used with variable success. Isolated reports suggest benefit from oral psoralen and ultraviolet A phototherapy, topical salicylic acid, and corticosteroids. PREVENTION There is no effective prevention other than keeping up with age-appropriate cancer screenings.
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