A 70-year-old male presents to your office for evaluation of an extremely pruritic rash that initially started on his ears and fingers and has spread to involve his fingernails, palms, soles, and cheeks. Photographs of the ear and plantar feet are shown below.

Which of the following malignancy is the patient most at risk for?

A. Adenocarcinoma of the colon

B. Squamous cell carcinoma of the nasopharynx

C. Hepatocellular carcinoma

D. B-cell lymphoma

E. Small cell lung cancer

Rationale: The findings above are representative of acrokeratosis paraneoplastica also known as Bazex syndrome. Acrokeratosis paraneoplastica is a paraneoplastic syndrome that has been described with 3 clinical phases. The first phase typically involves scaly papules on the digits, nose, and helices presenting as a nonspecific dermatitis. During the second phase, scaly plaques develop on the ears, lips, and cheeks and patients develop a keratoderma on the palms and soles. Nail involvement can occur at either the first or second stage and presents as nail thickening, hyperkeratosis, yellow discoloration, and pain. During the final stage, scaly plaques develop along the extremities, trunk, and scalp. Histology is generally not specific and demonstrates a psoriasiform dermatitis. Skin findings commonly precede the diagnosis of malignancy. Treatment is geared toward symptomatic management, commonly steroids and retinoids, and the most helpful treatment modality is the treatment of the underlying malignancy. 

Correct answer: B. Squamous cell carcinoma of the nasopharynx

Acrokeratosis paraneoplastica is most commonly associated with malignancies of the upper aerodigestive tract, particularly squamous cell carcinoma (SCC).

Incorrect answers: A, C, D, E

Acrokeratosis paraneoplastica is most commonly associated with cancers of the upper aerodigestive tract. The second most common malignancy is lung cancer. Malignancies of the genitourinary system, lower gastrointestinal tract, lymphomas/myelomas, and other locations have been reported but are less common.

Additional reading at Fitzpatrick's Dermatology Chapter 134: Cutaneous Paraneoplastic Syndrome

1. Shah MH, Ferrazzano C, Karthikeyan A, Hejazi H, Bhattacharya A, Andrew Awuah W, Isik A. Bazex Syndrome (Acrokeratosis Paraneoplastica): A Narrative Review of Pathogenesis, Clinical Manifestations, and Therapeutic Approaches. Cureus. 2023 Sep 16;15(9):e45368. doi: 10.7759/cureus.45368.