The clinical and histological features of 171 atypical fibroxanthomas (AFX) from a single institution in Western Australia are outlined. This area experiences high levels of solar radiation, and all assessable biopsies showed solar elastosis. Patients were aged between 41 and 97 years (median age 74), with 76% of tumors occurring in men (male to female ratio approximately 3 to 1). Most tumors were small, with a median diameter of 10 mm and a range of 4-35 mm. Only 5% exceeded 20 mm in diameter. Most AFX were well-circumscribed dermal lesions, with limited invasion of subcutis in a minority. Histological variants identified included keloidal (n = 8), clear cell (n = 3), and granular cell (n = 3), plaque like (n = 4), and myxoid (n = 1). Bland cytological appearances (spindle cell nonpleomorphic AFX) were noted in 5 tumors, with osteoclast-like giant cells in 2. Features suggesting regression were present in 22 cases. Two cases recurred locally, none metastasized. No tumors expressed melanocytic or epithelial markers. Seventy-four percent of cases expressed smooth muscle actin, typically strongly and diffusely. No AFX stained with desmin. Only 1 of 50 cases was CD117 positive. In conclusion, AFX may show a wide range of histological appearances, and a panel of immunohistochemical markers is essential to make the correct diagnosis. Histological mimics, such as poorly differentiated squamous cell carcinoma, must be carefully excluded. Specific diagnosis is important because there seems to be a very low risk of recurrence or metastasis despite the frequently alarming histology.

Distinction of basal and squamous cell carcinomas of the skin can be readily achieved with routine immunohistochemistry using Ber EP4 and EMA. Identification of basosquamous carcinoma is also facilitated with this method.

Incidence of MCC in WA is the highest reported in the literature. In addition, MCC has worse survival than melanoma. The high rates and demographic and anatomical distribution are consistent with sun exposure playing a causal role.

We examined the role of mast cell infiltrates and other clinical and histological factors in the prognosis of Merkel cell carcinoma. Mast cells were stained immunohistochemically in 36 Merkel cell carcinomas with an antibody to tryptase. The number of stainable cells was quantified within the tumors and surrounding stroma. Other clinical and histological parameters were examined, statistically analyzed, and compared to subsequent clinical course and prognosis. Patient prognosis was worse with higher tumor mast cell numbers (P < 0.002). Prognosis was also found to be adversely affected by the presence of lymphovascular invasion (P = 0.03) and increased tumor size (P = 0.05). Increased mast cells counts, tumor size, and lymphovascular invasion are associated with an adverse prognosis in Merkel cell carcinomas. Evaluation of mast cell infiltrates may provide useful prognostic data and ultimately could assist in selecting patients that require adjuvant treatment in this aggressive form of skin cancer.

The diagnosis of diffuse axonal injury (DAI), which may be of considerable importance in forensic medicine, necessitates widespread sampling of the brain for histology. Because a limited sampling method for screening brains for axonal damage would be of value for medico-legal work, the authors have tested the findings of an earlier study which suggested that a standard set of three blocks from above and below the tentorium could reliably be used in routine practice as a basis for the diagnosis of DAI. A series of 22 previously diagnosed cases of DAI, with a range of survival times, was studied using immunohistochemistry with antibodies to beta-amyloid precursor protein (beta APP), the microglial-associated antigen CD68 (PG-M1) and for GFAP. Strict histological criteria were used to assess traumatic damage, and the evolution of the histological changes with increasing survival is described. In four cases, the sampling scheme employed yielded evidence of axonal damage in only one block, and a diagnosis of DAI could have been made in only 13/22 cases. In six of the shortest surviving cases, beta APP positivity in the corpus callosum and brainstem outlined areas of early ischaemia, as well as of traumatic damage, so that interpretation of immunolabelling was not always clearcut The findings suggest that DAI cannot be reliably diagnosed on a restricted number of blocks from vulnerable areas, and that the use of beta APP and PG-M1 immunocytochemistry may bring interpretative problems that can only be resolved by taking a larger series of tissue samples for histology.