MOHS or MSC surgery is a technique that preserves healthy tissue as much as possible. Furthermore, the cure rate in primary carcinomas is 99%.

    Request medical consultation

    Fill out this form and we will contact you to advise you

    Micrographic Controlled Surgery without interruption (MOHS)

    Dr. Pablo Umbert, pioneer in Mohs surgery technique, dermatopathologist from Barcelona with more than 200 cases treated annually.

    MOHS surgery or CMM has no relation with the classical surgical excision, or the surgical study of the extracted specimen, where the histopathological information may give a false negative 5-10% (20). It also does not relate to the slow MOHS surgery for cutaneous sarcomas, which require several days between the paraffin process and a second intervention if results come out positive.

    What is MOHS surgery or CMM

    Mostly an outpatient procedure (95% of cases) with local anesthesia and without interruption.

    The patient has been previously informed of the different modalities in the treatment of his tumor and the possible risks and complications A list of medications that cannot be taken at least 7 days before the procedure is provided. If any of these medications are needed, the patient must share this with his/her dermatologist to find alternatives.

    The patient must have breakfast and a 5 mg valium is administered.

    Local anesthesia is given which lasts over 90 minutes. If needed, the sedation can be extended within a safety margin.

    The intervention is divided into different stages with 20 minutes time lapses, the necessary time to process the extracted tissue and provide an immediate histological result by an experienced dermatopathologist.

    Before the intervention, it is important to review the histological picture/image of the biopsy provided by the micrographic mohs surgeon to observe the histological pattern and facilitate readability during surgery.

    Surgical Technique

    Tumor is palped and its margins are observed with the tangential light, which show its edges. A line is drawn around its perimeter using a topical steryl colorant pencil.

    We eliminate the affected area macroscopically (debulking) with a superficial horizontal cut of the affected area. The three-dimensional image of the basal cell carcinoma helps determine the nature of the invasion of this tumor over healthy tissue.

    We initiate the technique two millimeters away from the excised area using a scalpel with an inclination of 45 degrees including epidermis and the rear face of the tumor on a single level/plane to avoid an uneven surface.

    The immediate histological examination of the tumor and all the area where the tumor was resting, as if being an open book, allows us to examine all of the histological area without leaving any room to leave behind any malignant cells.

    In order to achieve this there has to be a photographic match from the extracted tissue with the perform map where the tumor tissue is deposited, respecting the same orientation. The perimeter of the “piece” is marked with red and black dyes. These dyes, along with the epidermal curb, allow us to locate on a microscopic level any possible malignant cells.

    A cut is performed, with a thickness of 5 microns beginning from the back of the piece. Whether being a basal cell or a scaly cell carcinoma, it is introduced into the cryostat, under 20 ° C and stained with a special blue tincture (toluidine), whether it is a basal cell or a scally cell carcinoma.

    Final Stage in MOHS surgery or CMM

    When the last stage result shows negative, the tumor has been removed satisfactorily without sacrificing much healthy tissue. There is a guarantee of 97% success on primary carcinomas and a 93% on recurring ones that have been previously treated with other techniques.

    Histological Interpretation

    It is a simultaneous and immediate surgical and histological technique. It should be done by an experienced dermatopathologist with strong skills in reading and studying fresh tissue.

    The biggest difficulty is considering positive histological simulators: Table of false positives or false negatives.


    MOHS surgery or CMM give the best curable results for the treatment of carcinomas. The patient, in most cases, still retains his or her anesthetized area, but more anesthesia must be added within the safety margins because a larger area of skin tissue is needed for reconstruction.

    In large recurrent carcinomas, in high-risk locations, such as in the areas where the facial cranial nerves exit through the bone foramina, a total skin graft is advisable, to best stop a possible recurrence. We use flaps or edge-to-edge in most cases, due to their better aesthetic result and to be sure of the absence of tumor. In tumors such as giant centrofacial keratocanthoma or mutilating carcinomas, it is advisable to delay reconstruction (1-2 months) to easily detect a possible recurrence.

    Healing Expectations

    MOHS surgery or CMM give the best curable results for the treatment of carcinomas.

    Primary Carcinomas

    Other techniques 90% success

    MOHS Surgery 99% success

    Recurrent or high risk Carcinomas

    Blind techniques (no histological control) Electrocoagulation


    Laser co2 45% -60

    MOHS Surgery 94%

    Doctor Pablo Umbert