Living on the Edge: Diagnosing Sarcomatoid Melanoma Using Histopathologic Cues at the Edge of a Dedifferentiated Tumor: A Report of 2 Cases and Review of the Literature.

Sarcomatoid melanoma is a rare type of melanoma lacking typical histologic features of melanoma and often lacks expression of S100 protein and melanocyte-specific markers. Given the rarity of this entity, its clinicopathologic findings are not well defined. We report 2 cases of sarcomatoid melanoma received in consultation: a 65-year-old woman with a right breast mass and a 62-year-old man with a left plantar heel mass. Both lesions were ulcerated, pedunculated, highly cellular proliferations of atypical spindle cells arranged as fascicles and/or sheets. The tumor cells of the breast mass expressed CD10 and vimentin diffusely but S100 protein only focally. The tumor cells of the heel mass lacked expression of melanocytic markers altogether, except for weak, very focal S100 protein expression. At the junctional edge of the breast mass and in the ulcer base of the heel mass, focal precursor melanoma was present and exhibited melanocytic differentiation. We report these cases to emphasize the importance of meticulous histologic inspection at the lesion's edge and/or ulcer base to correctly identify the conventional precursor melanoma in these rare lesions to ensure appropriate diagnosis and subsequent clinical management as treatment options may be significantly different from those offered for sarcomas.

Broadening the Anatomic Landscape of Sclerosing Perineurioma: A Series of 5 Cases in Nonacral Sites.

Sclerosing perineurioma is a rare perineurioma variant thought to occur almost exclusively in digits and palms, predominantly in young adult men. It clinically presents as a solitary slow-growing nodule, sometimes associated with prior trauma. Since 01/01/2000, our institution has received 5 cases in consultation of sclerosing perineurioma presenting in atypical locations. Four of 5 patients were women. The median age at presentation was 45 years (range, 31-62 years). Sites included dorsal tongue, anterior neck, mid upper back, forearm, and proximal anterior thigh. Complete clinical histories were not available, although lesions were reported as subcentimeter nodules with at least 1 suspected to have formed after trauma. Histologically, all lesions were circumscribed to dermal/submucosal tumors. Some extended into subcutaneous fat. The neoplasms were composed of an admixture of bland spindled to epithelioid cells with uniform, wavy, thin-to-oval nuclei forming linear cords to whorled sheets in an extensively hyalinized stroma. Mitotic activity was inconspicuous. All tumors expressed epithelial membrane antigen and were negative for S100 protein. All cases stained for CD34 were positive (3/3). This series highlights a broader clinical presentation of sclerosing perineurioma than previously recognized. Acknowledgment of this anatomic variability should provide confidence to dermatopathologists faced with similar cases.

Desmoplastic melanoma presenting as primary alopecia neoplastica: a report of two cases.

Desmoplastic melanoma is an uncommon form of melanoma characterized by atypical spindled melanocytes and abundant collagen deposition. It typically presents in sun-damaged skin of the elderly as an amelanotic, indurated lesion. It has a higher tendency for local recurrence but lower risk of lymph node metastasis vs. conventional malignant melanoma. We report two cases in women aged 59 and 66 who presented with small scalp lesions clinically suggestive of alopecia. The differential diagnosis included alopecia areata, lupus erythematosus and lichen planopilaris. Biopsies performed according to alopecia protocol were reviewed at our institutions. Biopsies revealed atypical spindled and nested epithelioid melanocytes set in a sclerotic dermis with scattered lymphoid aggregates and immunohistochemical expression of S100 protein, features diagnostic of combined desmoplastic melanoma. Wide local excision with skin graft was performed on the older patient. Excision showed combined desmoplastic melanoma with a Breslow thickness of 8.5 mm with melanoma in situ identified in the adjacent epidermis. The other patient sought treatment elsewhere and was lost to follow up. These cases illustrate desmoplastic melanoma as an unusual etiology and dangerous clinical pitfall in patients with scar-like alopecia. To the authors' knowledge, these represent the second and third reported cases of desmoplastic melanoma presenting as primary alopecia neoplastica.

Prognostic Significance of "Nonsolid" Microscopic Metastasis in Merkel Cell Carcinoma Sentinel Lymph Nodes.

Our recent work regarding Merkel cell carcinoma sentinel lymph node (SLN) metastasis found that "solid" pattern microscopic metastasis conferred worse prognosis than the "nonsolid" ones. The goals of the present study were to (1) compare the prognostic significance/outcomes of 2 diagnostic groups-patients with a nonsolid pattern of SLN metastasis and those with diagnostically negative SLN biopsies (SLNB), and (2) evaluate the durability of SLN metastasis after extensive sectioning. Five-level, step-wise sectioning at 250-µm intervals was performed in all SLN blocks with an immunohistochemical stain for CK20 on all levels. The presence and pattern of metastases were recorded and analyzed as were corresponding patient and tumor parameters. Median follow-up durations for all patients (n=38), positive SLNB (n=16) and negative SLNB (n=22) groups were 56.3, 50.4, and 66.8 months, respectively. Overall survival (OS) and disease-specific survival (DSS) did not differ between the 2 diagnostic groups (OS P=0.65, DSS P=0.37) but did differ by immune status (immunocompetent vs. immunosuppressed, OS P=0.03, DSS P=0.005) and primary tumor category (OS P<0.0001, DSS P=0.001). On deeper sectioning, all 16 diagnostically positive SLNB continued to show nonsolid microscopic metastasis, and 32% (7/22) diagnostically negative SLNB revealed nonsolid metastasis. DSS was worse for sinusoidal-pattern metastasis versus all others (P=0.02). Five of 38 patients (13%) died of disease; the only immunocompetent patient had sinusoidal-pattern metastasis discovered in a diagnostically negative SLNB. Our data suggest that outcome for nonsolid metastasis is similar to that of negative SLNB with the exception of the sinusoidal pattern, which was associated with worse outcome. Larger studies are warranted to quantify and compare microscopic metastatic tumor burden by pattern and confirm whether the sinusoidal pattern confers an intermediate prognostic risk between solid and other nonsolid microscopic metastases.

Pituitary aspergillus infection.

Fungal infection should be considered in the differential diagnosis of a pituitary or sellar mass, albeit fungal infections involving the pituitary gland and sella are a rare occurrence. We report a case of Aspergillus infection involving the pituitary gland and sellar region discovered in a 74-year-old man. The patient had a history of hypertension, chronic renal disease, autoimmune hemolytic anemia and presented with right eye pain, headaches and worsening hemiparesis. Imaging studies revealed a right internal carotid artery occlusion and an acute right pontine stroke along with smaller infarcts in the right middle cerebral artery distribution. Clinically, the patient was thought to have vasculitis. An infectious etiology was not identified. He developed respiratory distress and died. At autopsy, necrotizing meningitis was discovered. A predominantly chronic inflammatory cell infiltrate consisting of benign-appearing lymphocytes, plasma cells and macrophages was accompanied by acute angle branching, angioinvasive hyphae which were highlighted on Gomori methenamine silver staining and were morphologically consistent with Aspergillus species. In previously reported cases of Aspergillus infection involving the pituitary or sella, most presented with headaches or impaired vision and were not immunocompromised. A transsphenoidal surgical approach is recommended in suspected cases in order to minimize the risk of dissemination of the infection. Some patients have responded well to antifungal medications once diagnosed.