Late-Onset Acrokeratosis Paraneoplastica of Bazex Associated With Metastatic Adenocarcinoma of the Colon

A myriad of nonspecific histologic features of AP commonly reported include hyperkeratosis, parakeratosis, acanthosis, and dermal perivascular lymphohistiocytic infiltrate.⁷ Less common features include dyskeratotic keratinocytes, vacuolar degeneration, bandlike infiltrate, and melanin incontinence.⁷ The pathogenesis of AP remains elusive. A postulated immunologic mechanism is based on reports of immunoglobulins (IgG, IgA, IgM) and complement (C3) deposition along the basement membrane zone.⁸ Association with autoimmune disorders such as alopecia areata and vitiligo also has been reported.⁹ Another possible mechanism is cross-reactivity between antigens found in the tumor and skin, resulting in a T-cell–mediated immune response to tumorlike antigens in the epidermis, or secretion of tumor-originating growth factors responsible for the hyperkeratotic skin changes, such as epidermal growth factor, transforming growth factor a, or insulinlike growth factor 1.^3,7,10,11

Spontaneous remission of cutaneous lesions in untreated underlying malignancy is rare. Isolated reports of treatment using topical and systemic steroids, salicylic acid, topical vitamin D analogues, etretinate, and psoralen plus UVA showed minimal improvement.^5,7 The mainstay in attaining cutaneous resolution is to detect and eradicate the underlying neoplasm with surgery, chemotherapy, or radiotherapy, or combination therapy.

Our case is noteworthy because of the patient’s gender (female), underlying malignancy (adenocarcinoma of the colon), and late onset of cutaneous involvement, which are all uncommon associations related to paraneoplastic syndrome. The clinical features of AP should be recognized early to facilitate an extensive search for an occult malignancy, and late-onset cutaneous involvement also should be recognized as a marker of tumor relapse or progression.