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Case 1150: A Man in His 60s with Upper Lip Lesion

Contributed By: Daisy Wu, MD, Diana M. Bell, MD

Clinical History

A man in his seventh decade of life presents with an upper lip lesion present for the past 10 years. Throughout the past decade, he has been noting slight growth of the lesion and occasionally accidentally cutting over his skin over the lesion during shaving.

Gross Findings:

Lip resection demonstrates a 2.0 x 1.1 x 0.5 cm raised irregular ill-defined subcutaneous lesion under tan-gray and tan-pink mucosa (see Fig. 1).
 

Figure 1
Figure 1. Representative cross section of the lesion (white-tan subcutaneous stellate lesion under pink tan mucosa).

Histopathologic Features:

Histological analysis of lesion demonstrates subcutaneous sclerosing basaloid infiltrative solid nests, strands and columns of small monomorphous epithelial cells and ductal structures composed of two layers of small cuboidal cells obliterating adnexal structures within the region (Fig. 2). These lesional cells also demonstrate infiltration into adjacent skeletal muscle as well as perineural invasion (Fig. 3). The tumoral cells forming ducts also occasionally demonstrate eosinophilic concentric secretions consistent with keratin suggestive of trichilemmal differentiation.

Whole slide images for this case can be viewed at (use theViewOnline links): Digital Slide Viewer: MAC

Figure 2
Figure 2. Low power view of lesion. The lesion consists of infiltrative basaloid solid nests, strands and ductal structures. The obliteration of normal adnexal structures by the lesion is evident in this image between the two black arrows as well as infiltration into the skeletal muscle (labeled *).
Figure 3
Figure 3. Example of tumoral cells demonstrating perineural invasion.
Figure 4
Figure 4. Examples of tumoral ductular structures with concentric eosinophilic laminar secretions consistent with “wet keratin” suggestive of trichilemmal differentiation.

Immunoperoxidase studies was performed on the lesion including p40, CK5/6, CK7, CK34, CEA-M, SOX-10 and Ki-67. Tumor cells were diffusely positive for p40, CK5/6, CK34, patchy positive for CK7, negative for CEA-M and SOX-10 and a Ki-67 proliferative rate around 3%.

Molecular findings:

UPMC Oncomine Test demonstrated an ARID1A p.Q766* mutation, ROS1 p.P1941Lfs*5 variant of uncertain significance and RAD51D p.Q177L variant of uncertain significance. The tumor mutation burden was at the 36 percentile.

What is the diagnosis?

Diagnosis and Discussion