Microwave Processing Cuts Time for Creating Mohs Specimens

NAPLES, FLA. — Microwave-assisted processing of permanent paraffin sections takes much less time than the conventional paraffin embedding process for Mohs surgery specimens, yet preserves its advantages over frozen sections in visualizing melanoma in situ, Dr. Raj Mallipeddi said at the annual meeting of the American College of Mohs Surgery.

Permanent paraffin sections are considered the standard for assessing histology, but the long time required to process them may make Mohs surgery inefficient because patients must return at least 24 hours later for additional Mohs stages or the repair procedure. Frozen sections also are considered by some clinicians to be inadequate to identify atypical melanocytes reliably, said Dr. Mallipeddi, a procedural dermatology fellow at the University of Texas Southwestern Medical Center, Dallas. Microwave tissue processing is "nothing new," and has been used in a variety of histologic procedures in the past few decades.

Dr. Mallipeddi and his associates divided 13 specimens of melanoma in situ from the initial debulking stage of surgery into 4 pieces each. They processed the pieces from each specimen using four different methods. The conventional method was used to create permanent paraffin sections, as was the group's rapid microwave technique. The researchers also made frozen sections stained with hematoxylin and eosin, and frozen sections immunostained with antibodies against MART-1, a protein found on melanocytes.

An experienced Mohs surgeon and a dermatopathologist compared all of the sections in a blind fashion to determine if there were any differences in the ability to visualize normal and abnormal melanocytes, and in the overall ability to see the epidermis and dermis.

There were no significant differences between the two paraffin techniques on those three criteria. The microwave paraffin sections proved to be significantly better than the frozen hematoxylin and eosin sections on all three criteria. Abnormal melanocytes could be visualized significantly better with the microwave paraffin technique than with frozen MART-1 sections, but the microwave method was similar to frozen MART-1 sections in identifying normal melanocytes. At 200× magnification, the morphology of atypical melanocytes was seen clearly with the microwave technique. MART-1 immunostaining on frozen sections showed melanocyte density well, but individual cell morphology was "not so well depicted," Dr. Mallipeddi said.

The method produces permanent paraffin sections in about 2 hours. The procedure involves fixing fresh tissue for 30 minutes, microwave processing for another 30 minutes, embedding the tissue in paraffin, and then staining the specimen with hematoxylin and eosin for about 10 minutes.

"We believe this technique should be investigated further in the context of Mohs micrographic surgery—not just for melanoma in situ," Dr. Mallipeddi said.

NAPLES, FLA. — Microwave-assisted processing of permanent paraffin sections takes much less time than the conventional paraffin embedding process for Mohs surgery specimens, yet preserves its advantages over frozen sections in visualizing melanoma in situ, Dr. Raj Mallipeddi said at the annual meeting of the American College of Mohs Surgery.

Permanent paraffin sections are considered the standard for assessing histology, but the long time required to process them may make Mohs surgery inefficient because patients must return at least 24 hours later for additional Mohs stages or the repair procedure. Frozen sections also are considered by some clinicians to be inadequate to identify atypical melanocytes reliably, said Dr. Mallipeddi, a procedural dermatology fellow at the University of Texas Southwestern Medical Center, Dallas. Microwave tissue processing is "nothing new," and has been used in a variety of histologic procedures in the past few decades.

Dr. Mallipeddi and his associates divided 13 specimens of melanoma in situ from the initial debulking stage of surgery into 4 pieces each. They processed the pieces from each specimen using four different methods. The conventional method was used to create permanent paraffin sections, as was the group's rapid microwave technique. The researchers also made frozen sections stained with hematoxylin and eosin, and frozen sections immunostained with antibodies against MART-1, a protein found on melanocytes.

An experienced Mohs surgeon and a dermatopathologist compared all of the sections in a blind fashion to determine if there were any differences in the ability to visualize normal and abnormal melanocytes, and in the overall ability to see the epidermis and dermis.

There were no significant differences between the two paraffin techniques on those three criteria. The microwave paraffin sections proved to be significantly better than the frozen hematoxylin and eosin sections on all three criteria. Abnormal melanocytes could be visualized significantly better with the microwave paraffin technique than with frozen MART-1 sections, but the microwave method was similar to frozen MART-1 sections in identifying normal melanocytes. At 200× magnification, the morphology of atypical melanocytes was seen clearly with the microwave technique. MART-1 immunostaining on frozen sections showed melanocyte density well, but individual cell morphology was "not so well depicted," Dr. Mallipeddi said.

The method produces permanent paraffin sections in about 2 hours. The procedure involves fixing fresh tissue for 30 minutes, microwave processing for another 30 minutes, embedding the tissue in paraffin, and then staining the specimen with hematoxylin and eosin for about 10 minutes.

"We believe this technique should be investigated further in the context of Mohs micrographic surgery—not just for melanoma in situ," Dr. Mallipeddi said.

NAPLES, FLA. — Microwave-assisted processing of permanent paraffin sections takes much less time than the conventional paraffin embedding process for Mohs surgery specimens, yet preserves its advantages over frozen sections in visualizing melanoma in situ, Dr. Raj Mallipeddi said at the annual meeting of the American College of Mohs Surgery.

Permanent paraffin sections are considered the standard for assessing histology, but the long time required to process them may make Mohs surgery inefficient because patients must return at least 24 hours later for additional Mohs stages or the repair procedure. Frozen sections also are considered by some clinicians to be inadequate to identify atypical melanocytes reliably, said Dr. Mallipeddi, a procedural dermatology fellow at the University of Texas Southwestern Medical Center, Dallas. Microwave tissue processing is "nothing new," and has been used in a variety of histologic procedures in the past few decades.

Dr. Mallipeddi and his associates divided 13 specimens of melanoma in situ from the initial debulking stage of surgery into 4 pieces each. They processed the pieces from each specimen using four different methods. The conventional method was used to create permanent paraffin sections, as was the group's rapid microwave technique. The researchers also made frozen sections stained with hematoxylin and eosin, and frozen sections immunostained with antibodies against MART-1, a protein found on melanocytes.

An experienced Mohs surgeon and a dermatopathologist compared all of the sections in a blind fashion to determine if there were any differences in the ability to visualize normal and abnormal melanocytes, and in the overall ability to see the epidermis and dermis.

There were no significant differences between the two paraffin techniques on those three criteria. The microwave paraffin sections proved to be significantly better than the frozen hematoxylin and eosin sections on all three criteria. Abnormal melanocytes could be visualized significantly better with the microwave paraffin technique than with frozen MART-1 sections, but the microwave method was similar to frozen MART-1 sections in identifying normal melanocytes. At 200× magnification, the morphology of atypical melanocytes was seen clearly with the microwave technique. MART-1 immunostaining on frozen sections showed melanocyte density well, but individual cell morphology was "not so well depicted," Dr. Mallipeddi said.

The method produces permanent paraffin sections in about 2 hours. The procedure involves fixing fresh tissue for 30 minutes, microwave processing for another 30 minutes, embedding the tissue in paraffin, and then staining the specimen with hematoxylin and eosin for about 10 minutes.

"We believe this technique should be investigated further in the context of Mohs micrographic surgery—not just for melanoma in situ," Dr. Mallipeddi said.