[491] The Value of Nuclear Morphometry in Malignant Versus Benign Parakeratosis

J Song, CR Shea. University of Chicago, Chicago

Background: Shave biopsies of skin, despite being convenient and minimally invasive, can sometimes have inadequate depth. A shave biopsy composed mainly of stratum corneum can pose a diagnostic challenge. Parakeratosis occurs in both benign and malignant diseases. Even though parakeratotic nuclei are often pyknotic, malignant ones do appear somewhat atypical in our experience. Nuclear morphometry could provide relevant information in these cases, an approach that has not been investigated in the literature. In this context, we studied the value of nuclear morphometry of parakeratosis in routine H&E slides from benign and malignant skin biopsies.
Design: Squamous cell carcinoma (SCC) and psoriasiform dermatitis (PD) cases with significant parakeratosis were selected during a 2-month period (12 SCC, 14 PD). Digital images (400 X, 1300 x 1030 pixels) were taken in parakeratotic areas of stratum corneum. Nuclear identification and morphometry were performed using the automated, open-source software CellProfiler running on an Intel PC. Statistical analysis was conducted by t-test.
Results: Each case had 126 to 768 well-visualized parakeratotic nuclei (mean 337). Significant differences were found between SCC and PD in nuclear area, area variability (the standard deviation among all nuclei of one case), form factor, and short axis (Table 1). Form factor, defined as (4 pi) Area/Perimeter², correlates with nuclear convolution or indentation (1 for perfectly round objects). Nuclear area alone could discriminate between most cases of SCC and PD. There was not much difference between SCC and PD in nuclear perimeter or long axis, probably because all parakeratotic nuclei, including benign ones, tend to be elongated.

Table 1. Nuclear morphometric parameters.

Parameter (Mean SD)	SCC	PD	P value
Area	355 75	234 45	< 0.0001
Area Variability	176 51	92 28	< 0.0001
Perimeter	86 11	78 6	0.02
Form factor	0.57 0.1	0.47 0.07	0.005
Long Axis	36 6	35 3	0.57
Short Axis	12 2	8 1	< 0.0001

Unit, pixel (1 pixel = 0.22 micron).


Conclusions: Nuclear morphometry may provide valuable objective information in the differential diagnosis of benign and malignant parakeratosis, a situation that may be encountered in very superficial shave biopsies. Accurate morphometry can be performed with free, open-source software, and requires little special knowledge of image analsysi or programming, making it an affordable and widely adaptable approach.
Category: Dermatopathology

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 67, Tuesday Afternoon