Atypical Granular Cell Tumor

This 55 yo woman was seen for three painful lesions (left abdomen of two months duration and right axilla of one week duration).  She is in good general health and takes no medications by mouth.

Pathology of lesion abdomen:

Granular cell tumor with atypical features consistent with at least "atypical granular cell tumor."

NOTE: The specimen exhibits a diffuse dermal interstitial proliferation of S100-protein positive and CD68 positive epithelioid cells with abundant finely granular, eosinophilic cytoplasm that is negative for high and low molecular weight keratins and Mart-1/Melan-A. The granular cells show nuclei that are variably pleomorphic as well as that are intermittently vesicular with large nucleoli. These changes are diffuse throughout the tumor and are consistent with the atypical variant of granular cell tumor.  The photomicrographs are courtesy of Dr. Hyejin Leah Chung , a dermatopathology fellow at Boston University School of Medicine.  (They are 10x, 20x, 40x and 40x)

Axillary Lesion: Inflammatory nodule consisten with hidradenitis.

Diagnosis: Atypical granular cell tumor is a problematic diagnosis.  A small percentage of these may be malignant granular cell tumors and they have a worrisome behavior.  The fact that the axillary lesions are presumably not related is curious.  This patient needs a full work-up and follow-up.

Referencea:
1. Case for diagnosis.

Leyva AM et.al.  An Bras Dermatol. 2014 May-Jun;89(3):523-4.

Abstract: Granular cell tumour is a rare tumour of neural origin usually located on the face and the neck. The biological behaviour is usually benign. However, certain clinical and histopathological features should alert physicians to a malignant behaviour. This case report describes the occurrence of a granular cell tumour in the inguinal area that resembled a malignant tumour. The histopathological study revealed typical features of granular cell tumour and an extension study confirmed the absence of metastasis. This case highlights the importance of considering this disorder in the differential diagnosis of ulcerated nodules and of managing atypical granular cell tumor appropriately.  Free Full Text.