Adenosquamous Carcinoma Is Aggressive, Easily Missed

VANCOUVER, B.C. — Adenosquamous carcinoma is an often misdiagnosed and more aggressive type of skin cancer that requires close follow-up for possible recurrences, according to a review that identified 27 patients with primary disease.

"We are starting to get the sense that it can be very clinically aggressive and, in fact, may be more aggressive than conventional cutaneous squamous cell carcinoma [SCC], with a high risk of local recurrence," Dr. Jennifer M. Fu said at the annual meeting of the American College of Mohs Surgery.

A rise in the number of cases at her institution in recent years, with some of them proving to be very locally aggressive, prompted a closer look at this cancer. Dr. Fu and her colleagues searched their institution's records for the past 10 years to identify cases of adenosquamous carcinoma (ASC) diagnosed there. The search identified 27 patients with primary ASC, 7 of whom experienced a recurrence. The patients had a mean age of 74 years (range 50-97 years), and 70% were men.

Some 56% of the primary tumors were on the face, 15% were on the scalp, and 15% were on the arm or shoulder. "Clinically, this was a very difficult diagnosis for people to make, often presenting just as a firm papule or plaque and not infrequently ulcerated," observed Dr. Fu, a dermatology resident at the University of California, San Francisco.

"Most of the clinicians diagnosed this as something else—as basal cell carcinoma, scar, metastatic carcinoma, rosacea in one case, and a spider bite in another case," she said. "In no case was adenosquamous carcinoma correctly diagnosed."

Histopathologically, many of the features of ASC overlap those of desmoplastic SCC, but ASC differs in having glandular differentiation. "At least at our institution, we feel that adenosquamous carcinoma is probably best considered a variant of SCC and on a spectrum of desmoplastic SCC," Dr. Fu said.

The tumors evaluated in the study typically had an infiltrative pattern with dermal fibrosis or sclerosis: 61% showed elastosis, while 30% were ulcerated. Squamous differentiation was universal, with all tumors exhibiting cytoplasmic cornification and 41% having keratinizing cysts.

Most tumors (92%) had ductular elements, while 58% had glandular elements. Even when a tumor had glandular elements, the percentage of that tumor showing those elements varied from roughly 5% to 80%. In fact, two of the cases were initially interpreted to be SCC but were subsequently determined to have glandular differentiation more consistent with ASC. In such equivocal cases, immunostaining for carcinoembryonic antigen or cytokeratin 7 may help identify glandular foci, she noted.

Clinical outcomes were assessed in the six patients who received most of their treatment at her hospital. Five were immunosuppressed. All underwent Mohs surgery at least once, and two received adjuvant radiation therapy and cetuximab (Erbitux) for locally advanced disease. For these patients, "the Mohs defect postoperatively far exceeded what was evident clinically," said Dr. Fu, who had no conflicts of interest in association with the study.

In this patient, recurrent nodules and plaques of adenosquamous carcinoma are visible at the edge of a scar from previous treatment. University of California, San Francisco/Department of Dermatology

VANCOUVER, B.C. — Adenosquamous carcinoma is an often misdiagnosed and more aggressive type of skin cancer that requires close follow-up for possible recurrences, according to a review that identified 27 patients with primary disease.

"We are starting to get the sense that it can be very clinically aggressive and, in fact, may be more aggressive than conventional cutaneous squamous cell carcinoma [SCC], with a high risk of local recurrence," Dr. Jennifer M. Fu said at the annual meeting of the American College of Mohs Surgery.

A rise in the number of cases at her institution in recent years, with some of them proving to be very locally aggressive, prompted a closer look at this cancer. Dr. Fu and her colleagues searched their institution's records for the past 10 years to identify cases of adenosquamous carcinoma (ASC) diagnosed there. The search identified 27 patients with primary ASC, 7 of whom experienced a recurrence. The patients had a mean age of 74 years (range 50-97 years), and 70% were men.

Some 56% of the primary tumors were on the face, 15% were on the scalp, and 15% were on the arm or shoulder. "Clinically, this was a very difficult diagnosis for people to make, often presenting just as a firm papule or plaque and not infrequently ulcerated," observed Dr. Fu, a dermatology resident at the University of California, San Francisco.

"Most of the clinicians diagnosed this as something else—as basal cell carcinoma, scar, metastatic carcinoma, rosacea in one case, and a spider bite in another case," she said. "In no case was adenosquamous carcinoma correctly diagnosed."

Histopathologically, many of the features of ASC overlap those of desmoplastic SCC, but ASC differs in having glandular differentiation. "At least at our institution, we feel that adenosquamous carcinoma is probably best considered a variant of SCC and on a spectrum of desmoplastic SCC," Dr. Fu said.

The tumors evaluated in the study typically had an infiltrative pattern with dermal fibrosis or sclerosis: 61% showed elastosis, while 30% were ulcerated. Squamous differentiation was universal, with all tumors exhibiting cytoplasmic cornification and 41% having keratinizing cysts.

Most tumors (92%) had ductular elements, while 58% had glandular elements. Even when a tumor had glandular elements, the percentage of that tumor showing those elements varied from roughly 5% to 80%. In fact, two of the cases were initially interpreted to be SCC but were subsequently determined to have glandular differentiation more consistent with ASC. In such equivocal cases, immunostaining for carcinoembryonic antigen or cytokeratin 7 may help identify glandular foci, she noted.

Clinical outcomes were assessed in the six patients who received most of their treatment at her hospital. Five were immunosuppressed. All underwent Mohs surgery at least once, and two received adjuvant radiation therapy and cetuximab (Erbitux) for locally advanced disease. For these patients, "the Mohs defect postoperatively far exceeded what was evident clinically," said Dr. Fu, who had no conflicts of interest in association with the study.

In this patient, recurrent nodules and plaques of adenosquamous carcinoma are visible at the edge of a scar from previous treatment. University of California, San Francisco/Department of Dermatology

VANCOUVER, B.C. — Adenosquamous carcinoma is an often misdiagnosed and more aggressive type of skin cancer that requires close follow-up for possible recurrences, according to a review that identified 27 patients with primary disease.

"We are starting to get the sense that it can be very clinically aggressive and, in fact, may be more aggressive than conventional cutaneous squamous cell carcinoma [SCC], with a high risk of local recurrence," Dr. Jennifer M. Fu said at the annual meeting of the American College of Mohs Surgery.

A rise in the number of cases at her institution in recent years, with some of them proving to be very locally aggressive, prompted a closer look at this cancer. Dr. Fu and her colleagues searched their institution's records for the past 10 years to identify cases of adenosquamous carcinoma (ASC) diagnosed there. The search identified 27 patients with primary ASC, 7 of whom experienced a recurrence. The patients had a mean age of 74 years (range 50-97 years), and 70% were men.

Some 56% of the primary tumors were on the face, 15% were on the scalp, and 15% were on the arm or shoulder. "Clinically, this was a very difficult diagnosis for people to make, often presenting just as a firm papule or plaque and not infrequently ulcerated," observed Dr. Fu, a dermatology resident at the University of California, San Francisco.

"Most of the clinicians diagnosed this as something else—as basal cell carcinoma, scar, metastatic carcinoma, rosacea in one case, and a spider bite in another case," she said. "In no case was adenosquamous carcinoma correctly diagnosed."

Histopathologically, many of the features of ASC overlap those of desmoplastic SCC, but ASC differs in having glandular differentiation. "At least at our institution, we feel that adenosquamous carcinoma is probably best considered a variant of SCC and on a spectrum of desmoplastic SCC," Dr. Fu said.

The tumors evaluated in the study typically had an infiltrative pattern with dermal fibrosis or sclerosis: 61% showed elastosis, while 30% were ulcerated. Squamous differentiation was universal, with all tumors exhibiting cytoplasmic cornification and 41% having keratinizing cysts.

Most tumors (92%) had ductular elements, while 58% had glandular elements. Even when a tumor had glandular elements, the percentage of that tumor showing those elements varied from roughly 5% to 80%. In fact, two of the cases were initially interpreted to be SCC but were subsequently determined to have glandular differentiation more consistent with ASC. In such equivocal cases, immunostaining for carcinoembryonic antigen or cytokeratin 7 may help identify glandular foci, she noted.

Clinical outcomes were assessed in the six patients who received most of their treatment at her hospital. Five were immunosuppressed. All underwent Mohs surgery at least once, and two received adjuvant radiation therapy and cetuximab (Erbitux) for locally advanced disease. For these patients, "the Mohs defect postoperatively far exceeded what was evident clinically," said Dr. Fu, who had no conflicts of interest in association with the study.

In this patient, recurrent nodules and plaques of adenosquamous carcinoma are visible at the edge of a scar from previous treatment. University of California, San Francisco/Department of Dermatology