Daniel T. Finn

Microcystic Adnexal Carcinoma: A Rare, Locally Aggressive Cutaneous Tumor

To the Editor: Microcystic adnexal carcinoma (MAC) is an unusual cutaneous tumor with a propensity to be highly destructive, but rarely metastasize. The article “On the Surveillance, Epidemiology, and End Results (SEER) Database Analysis of Microcystic Adnexal Carcinoma of the Skin,” published in this issue of the American Journal of Clinical Oncology, reviews the data in 223 patients with this adnexal tumor from the National Cancer Institute SEER database. The authors are to be commended for validating several issues regarding the epidemiology, demographics, and natural history of MAC, which appeared consistent with previous case series. There are several points regarding this tumor that warrant further discussion. From the clinical perspective, the appearance of MAC is subtle and frequently overlooked, resulting in delayed diagnosis. MAC typically presents as an asymptomatic, solitary, indurated, ill-defined, skin-colored to yellow plaque, nodule, or cyst. Lesions are indolent, growing slowly for months to years before medical attention is sought. MAC can be easily confused with a benign adnexal tumor such as trichoepithelioma, trichoadenoma, and syringoma, or nonmelanoma skin cancers such as basal cell carcinoma or squamous cell carcinoma. Therefore, a skin biopsy should be considered for any slowgrowing, asymptomatic, indurated lesions, particularly in the head and neck regions. Whereas MAC rarely metastasizes, it often invades dermis, subcutaneous tissue, and can extend directly from the skin into muscle and bone, causing significant morbidity. Surgery remains the mainstay of treatment for MAC, and there are too few cases regarding the use of radiation as either primary or adjuvant therapy to make any judgments about its efficacy. The overall survival is excellent: patients with MAC have a tendency to live a normal lifespan, and are more likely to die of other causes. It should be noted that MAC was only recognized as a specific clinical entity in 1982. The rarity of this tumor and the infiltrative pattern of growth have resulted in only a small number of reports that evaluate the best treatment options. Therapies for MAC have included simple excision, Mohs micrographic surgery (MMS), chemotherapy, and radiation (either as a primary treatment or as an adjuvant therapy). In the study by Yu et al, based on National Cancer Institute SEER database from 1973 to 2004, a total of 195/223 (87%) MAC patients received surgical treatment (simple excision or Mohs). However, only 24 of the 195 surgical patients underwent MMS which over the last decade is gaining acceptance and considered by some as the treatment of choice for MAC. No cancer directed surgery was performed in 10% of patients. It is only recently that the utility of MMS has been recognized for treatment of many rare aggressive cutaneous tumors including dermatofibrosarcoma protuberans, extramammary Paget disease, and MAC, where clinical margins are difficult to define. The local recurrence rate for MAC in patients treated with a standard wide local excision reaches 17% to 60% compared with a maximum of 12% in those treated with MMS, based on a follow-up period of 6 weeks to more than 5 years in various series. The size of the defect after complete tumor removal following MMS can be as much as 4 to 6 times that of the clinically apparent size. Therefore, standardized and predetermined surgical margins are not as helpful in the treatment of MAC. Tumor size often plays a role in choosing treatment modalities. For very large tumors, radiation or chemotherapy is often the primary or an adjuvant treatment. Given the tumor’s rarity and paucity of reports in the literature, it is difficult to make recommendations regarding the use of radiation or chemotherapy for the treatment of MAC. In the current study by Yu et al, only 13 patients (6%) received postoperative adjuvant radiation therapy, and 1 patient ( 1%) received primary radiation treatment. There exists 1 case report of MAC possibly converting to a more histologically aggressive neoplasm postradiation treatment. Chemotherapy for MAC is not recorded in the SEER database. It has been difficult to draw any conclusions regarding these therapies for MAC given the small number of cases. It is also concerning that there were a large number of patients in this report for whom size of the tumor was not recorded (62%). Median recorded tumor size was 1.5 cm, similar to other series where median size has been reported as 2 cm. The authors did not comment on the presence of perineural invasion (PNI) in this cancer. MAC is a highly invasive tumor with a tendency to recur, particularly if PNI is observed histologically. Tumors exhibiting PNI are generally more aggressive, and manifest an increased rate of morbidity and mortality, especially in the head and neck region. MAC is an infiltrative tumor that is often associated with PNI with an incidence of 17.5% to 59% in various series. PNI is difficult to assess initially because of a lack of signs and symptoms in most patients. Symptoms generally present late in the course of disease, and include facial pain, anesthesia, and paresthesias (eg, tingling, burning, or pain) or motor impairments such as facial weakness, ptosis, diplopia, blurred vision, ophthalmoplegia, and fasciculations. The incidence of PNI and tumor recurrence is high for MAC; therefore, a high index of suspicion is necessary, and clinicians should inquire about specific signs and symptoms or perform appropriate neurologic testing. Surgery remains the standard treatment for MAC, with MMS emerging as a potential treatment of choice because of its lower rates of recurrence and morbidity when compared with traditional surgical techniques. Because of the paucity of data in the literature regarding use of radiation and chemotherapy for MAC, either as a monotherapy or adjuvant therapy are not yet defined. Of note, one of the risk factors for development of MAC is a history of radiation therapy. In summary, with appropriate care patients with MAC tend to have an excellent prognosis. Long-term data collection are needed both to better determine outcomes and the role of adjuvant therapies in the management of this entity.

Incidence of Invasive Squamous Cell Carcinomas in Biopsy‐Proven Squamous Cell Carcinomas In Situ Sent for Mohs Micrographic Surgery

BACKGROUND Squamous cell carcinoma (SCC) in situ (SCCIS) is often treated without any pathologic confirmation of tumor clearance. It is unclear how often an invasive SCC is harbored within a lesion in which the initial biopsy demonstrated SCCIS because of inadequate sampling. This study examines the final histologic diagnosis of cases in which the initial biopsies were diagnosed as SCCIS and evaluates factors that may correlate with a histologic upstaging of the diagnosis. METHODS We prospectively recruited 29 consecutive patients with biopsy‐proven SCCIS sent for Mohs micrographic surgery (MMS). Each tumor underwent MMS, and the central blocks of the Mohs debulking specimens were horizontally sectioned at 30‐&mgr;m intervals until exhausted. A fellowship‐trained Mohs surgeon and a board‐certified dermatopathologist processed and examined these sections to determine the final histologic diagnosis of the tumor. RESULTS Of the 29 subjects with biopsy‐proven SCCIS, nine were found to harbor invasive SCC on final histology. Of the remaining lesions, seven had residual SCCIS, whereas the rest exhibited only actinic keratoses or scars. Approximately 31% of lesions showed evidence of invasive SCC. Correlating the clinical characteristics of the lesions with their corresponding final histologic diagnoses, the lesions harboring invasive SCC were more likely to demonstrate clinical signs of residual tumor (scales and papular changes) and be larger than 1.4 cm in diameter. LIMITATIONS Our experience at a single institution in the northeastern United States may not be reflective of a wider population. There is also a possible referral bias, because only lesions with high clinical suspicion for invasive SCC were referred for MMS. CONCLUSION Although biopsy‐proven SCCIS is often treated with modalities that are best suited for superficial disease and do not involve a final pathologic confirmation of clearance (e.g., cryotherapy, electrodesiccation and curettage), this study demonstrated that up to 31% of biopsy‐proven SCCIS lesions may harbor invasive SCC. Clinical signs of residual tumor and a diameter larger than 1.4 cm are statistically significant predictors of underlying invasive SCC. These data suggest that treatment modalities that include histologic control of tumor removal should also be strongly considered for the treatment of select biopsy‐proven SCCIS meeting the above criteria.

Basal cell carcinoma invading the umbilical stalk excised with Mohs micrographic surgery: case report and review of umbilical anatomy.

&NA; The authors have indicated no significant interest with commercial supporters.

Crescent Versus Rectangle: Is It a True Negative Margin in Second and Subsequent Stages of Mohs Surgery?

BACKGROUND The hallmark of Mohs micrographic surgery is using tangential tissue sections that theoretically allow 100% of the tissue margin to be examined, but when taking additional layers for second and subsequent Mohs stages, no detailed methods have been described to ensure that 100% of the tissue margins are analyzed. METHOD A rectangular or a crescent‐shaped layer is often used to take second and subsequent stages. Here we compare the two techniques for their theoretic advantages and disadvantages. SUMMARY The advantage of the rectangular shape has been ease of processing, as well as built in vertical “nicks” that automatically mark the border of the tissue removed, but the rectangular layer may not provide 100% evaluation of the tumor margin because the vertical edges of the rectangular layer are not always completely analyzed, and thus tumor cells cannot be visualized in the vertical margins of these layers. This might result in a false‐negative margin reading, which can be avoided by using the crescent layer. CONCLUSION We propose taking second and subsequent Mohs layers with only a crescent shape, which allows true 100% tissue margin assessment. The authors have indicated no significant interest with commercial supporters.

Suspension Suture Technique to Prevent Nasal Valve Collapse After Mohs Micrographic Surgery

Nasal valve dysfunction, which results in poor air movement on inspiration due to a narrowed passageway or weakness of the internal (INV) or external nasal valve (ENV), is a common finding in dermatologic surgery involving the nasal ala, alar crease, and lateral sidewall. We present a suspension suture technique that can be performed at the time of skin lesion removal and reconstruction for effective prevention of nasal valve collapse.