Elastosis in granular cell tumours: prevalence and distribution

Atypical cytological presentation of granular cell tumour: Tumour-associated fibrosis may affect fine-needle aspiration cytology accuracy

The cytological features of granular cell tumour (GCT) are generally quite typical but, in some cases, the fine needle aspiration cytology (FNAC) diagnosis of GCT may be difficult or impossible because of unusual sites of onset or equivocal cytological features. In this report, two GCTs with atypical FNAC features are described in order to investigate the causes and provide possible diagnostic tips. From a series of nine histologically proven GCTs, two inconclusive FNAC cases were retrieved. Smears were poorly cellular showing isolated naked nuclei, anisonucleosis, granular chromatin and occasional small nucleoli. The background was finely granular in one case. Histological controls of these cases revealed marked fibrosis. Tumour-associated fibrosis in GCT is variable and does not seem to influence clinical behaviour but it influences the harvest and the integrity of granular cells collected by FNAC. When GCT smears are poorly cellular, attention should be paid to the granular background and to the few granular cells, if any, as they might be the only features to suggest a GCT.

Primary cutaneous malignant granular cell tumor: an immunohistochemical study and review of the literature. Am J Dermatopathol. 2015;37:334-340. [PMID: 25794371 DOI: 10.1097/dad.0000000000000106]

Granular cell tumors (GCTs) are uncommon soft tissue tumors characterized by cytoplasmic granular appearance of the neoplastic cells. Malignant granular cell tumors (MGCTs) comprise less than 2% of GCTs and are mostly found in the subcutaneous soft tissues of the lower extremities, especially the thighs. Very few cases have been reported in the skin. The uncommon occurrence of cutaneous MGCTs and their histopathologic similarities with their benign counterpart make difficult the diagnosis of this particular malignancy. We describe a primary cutaneous MGCT that presented as a left posterior chest wall mass in a 51-year-old woman. Local excision was performed for the primary tumor, which was first interpreted as an atypical GCT, but 3 months later a left axillary mass appeared, and subsequent axillary lymph node dissection demonstrated metastatic disease in 4 of 12 excised lymph nodes. We report the immunophenotype of this primary cutaneous MGCT, which was studied with an ample panel of antibodies and compare our results with those of the few previously reported cases in the skin and subcutaneous soft tissues.

Dermatofibroma with granular cells

A new histologic variant of dermatofibroma, only briefly alluded to in dermatological literature is reported. This tumor was located in the back of a 24-year-old man. It was present for about 2 years and had a history of trauma 2 months before excision. The lesion showed similar characteristics to those of conventional dermatofibroma as well as the presence of groups of granular cells identical to those seen in granular cell tumors. It is important to recognize dermatofibroma with granular cells because it may be confused with a variety of benign or malignant soft tissue tumors containing similar granular cells that entail different significance or prognosis. The immunohistochemical study supports a granular cell change in a dermatofibroma instead of a granular cell tumor that has been traumatized, with secondary formation of a dermatofibroma reaction.