Mohs frozen tissue sections in comparison to similar paraffin-embedded tissue sections in identifying perineural tumor invasion in cutaneous squamous cell carcinoma.

BACKGROUND: Perineural invasion (PNInv) in cutaneous squamous cell carcinoma (cSCC) increases the risk of recurrence, possibly because of suboptimal identification on frozen or paraffin-embedded tissue sections. Perineural inflammation (PNInf) may portend PNInv. OBJECTIVE: We sought to correlate identification of PNInv and PNInf in hematoxylin-eosin-stained Mohs frozen sections with PNInv and PNInf identified in similarly oriented paraffin-embedded sections obtained in cases of cSCC. METHODS: We reviewed same patient Mohs frozen and paraffin-embedded tissue sections for all patients presenting within a 2-year period to our Mohs micrographic surgical unit for removal of cSCC with PNInv or PNInf identified on either type of tissue section. RESULTS: Of 537 patients undergoing surgical resection of cSCC, 21 (3.9%) had either PNInv (n = 11) or PNInf (n = 10) on frozen sections. PNInv on Mohs frozen sections was identified in 11 cases and confirmed on paraffin-embedded sections in 9 cases (82%). Paraffin-embedded sections failed to identify PNInv present in Mohs frozen sections in two (2/11), or 18% of cases. PNInf on Mohs frozen sections was confirmed on paraffin-embedded sections in 3 cases (30%), but PNInv was identified in 5 cases (50%). LIMITATIONS: Our results are a retrospective case review from a specific time period by one institution. Furthermore, it is impossible to compare identical tissue specimens using two sequential tissue processing techniques. CONCLUSION: PNInv can be accurately identified with Mohs frozen sections. PNInf on Mohs frozen sections suggests the presence of PNInv and requires further histologic investigation.

The importance of reviewing pathology specimens before Mohs surgery.

BACKGROUND: The review of outside biopsy slides before performing surgery is the standard of care in many surgical specialties. Previous studies have shown high discrepancy rates between the original and second-opinion diagnoses. The frequency with which this practice changes the diagnosis and management of patients undergoing Mohs surgery is undocumented in the literature. It is standard practice at our institution to review all outside biopsy slides before Mohs surgery. OBJECTIVE: To investigate how often review of outside biopsies by an internal dermatopathologist changes patients' initial referral diagnosis and subsequent management. METHODS & MATERIALS: This is a retrospective review of all patients referred to Mohs surgery from January 2003 through March 2007. The number of cases in which the diagnosis changed and how this change affected management were recorded. RESULTS: Seventy-four of 3,345 (2.2%) cases were identified in which the diagnosis changed after review of the biopsy slides. Management was affected in the majority (61%) of cases. Board-certified dermatopathologists originally read nearly half of the biopsies. CONCLUSION: Review of outside biopsy slides before surgery can change the diagnosis in a large proportion of patients, with a resulting change in management. This quality-assurance practice may improve patient care.

Elastosis perforans serpiginosa.

A 41-year-old white man with Down syndrome presented with a slightly pruritic, papular eruption on bilateral forearms of several years' duration. Physical examination revealed multiple 2- to 3-mm keratotic, umbilicated pink papules in an annular configuration distributed symmetrically on the flexural surfaces of the forearms (Figure 1). The skin surrounding these papules was noted to be hyperpigmented and somewhat atrophic. The remainder of his skin examination was unremarkable. A shave biopsy of 1 papule was performed and stained with hematoxylin-eosin. Hematoxylin-eosin-stained sections showed clumps of bright red fibers being extruded through an acanthotic epidermis with a central invagination (Figure 2). Verhoeff-van Gieson stain confirmed these fibers to be elastin (Figure 3). Elastosis perforans serpiginosa was diagnosed.

Merkel cell carcinoma.

Merkel cell carcinoma is an aggressive tumor that should be treated early and aggressively. Although there are 5 published cases of spontaneous regression of Merkel cell carcinoma, a patient's best chance for survival is early detection with either wide local excision or Mohs' micrographically controlled margins with a final 5- to 10-mm layer. This should be followed by sentinel lymph node biopsy with lymph node dissection of the draining basin if metastases are discovered. Adjuvant radiation to the primary site and the draining basin should follow. Although this aggressive approach to treatment is not appropriate for every case, the literature, although scanty, supports this. Chemotherapy with or without additional radiation therapy should be offered to patients with advanced disease, mostly for palliation. The need for prospective trials and longer follow-up for larger series of patients is obvious.

Combined Merkel cell carcinoma and atypical fibroxanthoma.

BACKGROUND: Although there are reports of squamous cell carcinoma arising within and adjacent to Merkel cell carcinoma, and one report of an atypical fibroxanthoma-like tumor arising in an irradiated recurrent Merkel cell carcinoma, there have previously been no reports of an immunohistochemically verified atypical fibroxanthoma occurring in conjunction with a Merkel cell carcinoma. OBJECTIVE: We report on a neoplasm with distinct features of both Merkel cell carcinoma and atypical fibroxanthoma. METHODS: Histologic and immunohistochemical evaluations were performed. RESULTS: Our results verify the finding of a combined Merkel cell carcinoma and atypical fibroxanthoma. CONCLUSION: This case is an interesting and unusual combination of tumors. The origin of the Merkel cell carcinoma is revisited. Debated origins include neuroendocrine, epithelial, and pleuripotent stem cell.

White piedra: further evidence of a synergistic infection.

White piedra is a fungal infection of the hair shaft caused by Trichosporon beigelii. A synergistic coryneform bacterial infection is often present with T beigelii. White piedra, although not commonly reported to infect scalp hair in North America, is an important consideration in the differential diagnosis of scalp hair concretions. We report a case of white piedra of scalp hair with synergistic coryneform bacterial infection in two sisters, both US natives. Culture and light and electronmicroscopic evidence of the synergistic infection are presented.