Case Letter

Complete Remission of Metastatic Merkel Cell Carcinoma in a Patient With Severe Psoriasis

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Practice Points

  • Merkel cell carcinoma (MCC) has remarkable metastatic potential.
  • Initial evaluation of patients with MCC should include clinical examination to detect cutaneous, lymph node, and distant metastasis.
  • Risk factors associated with the development of MCC include immunosuppression, older age, and UV-exposed fair skin.


 

References

To the Editor:

A 69-year-old white man presented with a skin lesion on the back of 1 to 2 weeks’ duration. The patient stated he was unaware of it, but his wife had recently noticed the new spot. He denied any bleeding, pain, pruritus, or other associated symptoms with the lesion. He also denied any prior treatment to the area. The patient’s medical history was remarkable for severe psoriasis involving more than 80% body surface area, psoriatic arthritis, rheumatoid arthritis, ankylosing spondylitis, coronary artery disease, squamous cell carcinoma, and actinic keratoses. He had been on multiple treatment regimens over the last 20 years for control of psoriasis including topical corticosteroids, psoralen plus UVA and UVB phototherapy, gold injections, acitretin, prednisone, efalizumab, ustekinumab, and alefacept upon evaluation of this new skin lesion. Utilization of immunosuppressive agents also provided an additional benefit of controlling the patient’s inflammatory arthritic disease.

On physical examination a 0.6×0.7-cm, pink to erythematous, pearly papule with superficial telangiectases was noted on the right side of the dorsal thorax (Figure 1). Multiple well-demarcated erythematous plaques with silvery scale and areas of secondary excoriation were noted on the trunk and both legs consistent with the patient’s history of psoriasis.

Figure 1. A 0.6×0.7-cm, pink to erythematous, pearly papule with superficial telangiectases on the right side of the dorsal thorax consistent with Merkel cell carcinoma.

A shave biopsy was performed on the skin lesion on the right side of the dorsal thorax with a suspected clinical diagnosis of basal cell carcinoma. Two weeks later the patient returned for a discussion of the pathology report, which revealed nodules of basaloid cells with tightly packed vesicular nuclei and scant cytoplasm in sheets within the superficial dermis, as well as areas of nuclear molding, numerous mitotic figures, and areas of focal necrosis (Figure 2). In addition, immunostaining was positive for cytokeratin (CK) 20 antibodies with a characteristic paranuclear dot uptake of the antibody. These findings were consistent with a diagnosis of Merkel cell carcinoma (MCC). At that time, alefacept was discontinued and he was referred to a tertiary referral center for further evaluation and treatment.

Figure 2. Histopathology demonstrated islands of blue basaloid cells within the dermis displaying numerous mitotic figures and areas of necrosis (A–C)(all H&E, original magnifications ×4, ×20, and ×40).

The patient subsequently underwent wide excision with 1-cm margins of the MCC, with intraoperative lymphatic mapping/sentinel lymph node biopsy (SLNB) of the right axillary nodal basin 1 month later, which he tolerated well without any associated complications. Further histopathologic examination revealed the deep, medial, and lateral surgical margins to be negative of residual neoplasm. However, one sentinel lymph node indicated positivity for micrometastatic MCC, consistent with stage IIIA disease progression.

He underwent a second procedure the following month for complete right axillary lymph node dissection. Histopathologic examination of the right axillary contents included 28 lymph nodes, which were negative for carcinoma. He continued to do well without any signs of clinical recurrence or distant metastasis at subsequent follow-up visits.

Approximately 2.5 years after the second procedure, the patient began to develop right upper quadrant abdominal pain of an unclear etiology. Computed tomography of the abdomen and pelvis was performed, revealing areas of calcification and findings consistent with malignant lymphadenopathy. Multiple hepatic lesions also were noted including a 9-cm lesion in the posterior right hepatic lobe. Computed tomography–guided biopsy of the liver lesion was performed and the findings were consistent with metastatic MCC, indicating progression to stage IV disease.

The patient was subsequently started on combination chemotherapeutic treatment with carboplatin and VP-16, with a planned treatment course of 4 to 6 cycles. He was able to complete a total of 6 cycles over a 4-month period, tolerating the treatment regimen fairly well. Follow-up positron emission tomography–computed tomography was within normal limits with no evidence of any hypermetabolic activity noted, indicating a complete radiographic remission of MCC. He was seen approximately 1 month after completion of treatment for clinical follow-up and monthly thereafter.

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