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Background Floaters are dislodged pieces of tumor tissue than can obscure Mohs micrographic surgery (MMS) frozen sections and confound their interpretation. Objective To understand the common causes of floaters and identify management strategies. Methods An initial virtual consensus conference of Mohs surgeons based on a 60-item questionnaire. Data were validated in interviews with randomly selected Mohs surgeons. Results Based on retrospective reporting of 230 surgeon-years and 170,404 cases of MMS by 26 surgeons, the mean rate of floaters per tumor treated was 1.8%, and the rate of floaters per tissue block was 0.70%. Not wiping blades between cuts when a stage is separated into subunits can predispose to floaters. There was also strong consensus that basal cell carcinomas, ulcerated tumors, and tissue from the first stage were more likely to yield floaters. There is little consensus on how to manage floaters, with possibilities including taking additional sections, taking an additional stage, or simply noting the floater. Conclusion Floaters are not rare and can complicate MMS margin assessment. There is significant expert consensus regarding the causes of floaters and the tissue features that may predispose to them. Floaters may be prevented by minimizing their likely causes. There is less consensus on what to do with a floater.

Background Mohs micrographic surgery maximizes the potential for complete tumor removal with normal tissue preservation through the histologic examination of all tissue margins. One component of the histologic examination is the evaluation of excised nerves for the presence of tumor infiltration. During such an evaluation, a subperineurial structure was noted. Observation Further investigation displayed a discrete, loosely textured, cell-sparse, whorled, subperineurial structure that invaginated into the peripheral nerve. Inflammation was absent and the nuclei were monomorphous. These findings are those seen with Renaut bodies. Conclusions Renaut bodies are found at sites of nerve compression. Mechanical factors are thought to play a major role in pathogenesis. Cells comprising the Renaut body are fibroblasts of perineurial origin with the extracellular matrix comprised of collagen fibrils, basal lamina material, and oxytalan filaments. Renaut bodies are important insofar as the surgeon must recognize that they are benign. Histologic characteristics that differentiate Renaut bodies from malignant neurotropic infiltration are: (a) a cell-sparse mass, (b) absence of nuclear atypia, (c) less than expected inflammatory infiltrate, and (d) well-defined borders.

REPORT OF A CASE A 30-year-old woman presented with scattered, subtle red spots on her right upper extremity that had developed over the previous year. These spots were not tender or pruritic and exhibited no tendency for spontaneous resolution. This patient was particularly concerned that these lesions might continue to develop, because she had a far more extensive eruption in linear groups confined to the left side of her body. This latter eruption developed at age 6 months and had remained stable since. It was asymptomatic, except for its cosmetic implications. Besides the eruptions, she was in good health. The physical examination was notable for scattered erythematous, slightly atrophic maculae confined to the sun-exposed right upper extremity (Fig 1). A faint keratotic rim was visible around portions of the lesions. The left side of the trunk and the left upper and lower extremities had far more extensive linear groups of

Basal cell epithelioma (BCE) is the most common cutaneous malignancy. Primary BCE (ie, previously untreated) can be satisfactorily treated by a variety of methods, including curettage with electrodesiccation, scalpel excision, cryosurgery, and radiotherapy. Cure rates approach 98%. Recurrent BCE is much more difficult to treat and deserves particularly aggressive therapy, such as chemosurgery.

Squamous cell carcinomas of the fingers are uncommon tumors. While most of them pose little threat of metastasis, the clinician should know which tumors are likely to metastasize. Conservative surgical excision is the treatment of choice for squamous cell carcinoma of the finger. We present 19 cases treated conservatively with chemosurgery.

Chemosurgery and wound healing by secondary intention is an excellent method of treatment for subungual carcinoma. It allows for complete ablation of the tumour with maximal preservation of tissue, eliminating the need for amputation, in the absence of bone involvement. As most nail bed carcinomas occur on the thumb, by avoiding distal phalanx amputation one can prevent considerable disability. Because chemosurgery traces out every infiltrating band of tumour, bone involvement can be accurately detected. Amputation, if necessary, could then be carried out to achieve cure. Despite the age of our patients (average age 64.6 years), all surgical sites healed well with good range of motion at the adjecent interphalangeal joint.