Abstract:

A 75 year old male with chronic systolic congestive heart failure and cardiomyopathy of unspecified type presented with a 7x4mm tan nodule distorting lashes of the left lower eyelid. It had a pigmented center and was excised due to history of cutaneous melanoma of the back and squamous cell carcinoma of the antecubital area. Sections demonstrated an adnexal neoplasm with two interrelated patternsone comprised of cords of squamous epithelium with horn cyst formation and the other demonstrating a stratified squamous epithelium with a granular layer lining a cystic structure containing keratin. Some stroma of the lesion was replaced with amorphous pink material that demonstrated apple green birefringence with Congo red stain and positive jade green staining with sulfated Alcian blue, consistent with amyloid. Immunohistochemical stains showed positive reaction for HMW keratin in the amyloid and patchy reaction for CK7 at the periphery of the neoplasm and only focal weak positivity in the amyloid. Due to the patients cardiac history, it was deemed medically necessary to determine a definitive origin of the amyloid in order to rule out systemic amyloidosis. Liquid chromatography tandem mass spectrometry was performed on peptides extracted from Congo red-positive micro dissected areas of the paraffin-embedded specimen. Basal keratinocyte keratins 5 and 14 were detected, which is consistent with keratin-type amyloid deposition. Overall, we believe that the histopathologic and IHC features are most consistent with a tumor of follicular infundibulum. Keratin 5 and keratin 14 related amyloidosis is typically limited to skin and due to inflammatory or degenerative conditions that damage the basal keratinocytes resulting in subepidermal amyloid deposition and is not associated with systemic amyloidosis. We present this interesting case in order to elucidate the determination of the origin of amyloid in a setting where it is critical to rule out systemic amyloidosis.

Financial Disclosure:
No current or relevant financial relationships exist.

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Ashley Rose Scholl, MD, MSc