Abrikossoff's Tumor: An Unusual Presentation.

Abrikossoff's tumor or granular cell tumor is an infrequent benign neoplasm, first described by the Russian pathologist Abrikossoff in 1926. The neoplasm can affect all parts of the body with head and neck areas affected in 45-65% of patients. More than half of the head and neck lesions are localized to the oral cavity, especially the tongue. An aggressive malignant form of granular cell myoblastoma that metastasizes is rare. The treatment of choice of Abrikossoff's tumor is local surgical excision with a wide margin. Here, we present a case of Abrikossoff's tumor, occurring in the upper arm, presenting as a panniculitis-like lesion.

What was known?

Abrikossof's tumor is relatively rare, more commonly occurring in the head and neck regions

It usually presents as a papulo nodule.

Introduction

Abrikossoff's tumor or granular cell tumor (GCT) is usually benign, involving multiple anatomical sites, most frequently the head, neck, and airways. Occasional observations of aggressive malignant tumors have been reported, associated with a poor prognosis.

Case Report

We report a 53-year-old lady who presented to us with a hyperpigmented depressed plaque over her right upper arm of 3 cm × 2 cm of 2 years duration [Figure 1]. It was firm with mild tenderness and was gradually increasing in size. There was no history of discharge from the lesion neither were there any systemic complaints. There was no regional lymphadenopathy. A clinical differential diagnosis of subcutaneous morphea or subcutaneous granuloma annulare was made.

Figure 1

A hyperpigmented depressed plaque in the right upper arm

Histopathology of the lesion revealed a non-encapsulated tumor mass in the dermis and subcutaneous tissue composed of irregularly arranged sheets of large polyhedral cells with indistinct cytoplasmic membranes [Figure 2]. They were found to have an abundant eosinophilic granular cytoplasm, round to oval nucleus, and a small nucleolus. In some places, the granules had formed larger masses called ‘pustulo-ovoid bodies of milian,’ which were surrounded by a clear halo [Figure 3]. The granules were diastase-resistant and PAS-positive [Figure 4]. The overlying epidermis was normal and did not show hyperplasia. Hence, a histological diagnosis of a benign granular cell tumor was made. Our patient underwent a surgical resection of the tumor.

Figure 2

Section of skin showing the tumor mass in the subcutaneous tissue with large polyhedral cells and a granular cytoplasm (H and E, ×100)

Figure 3

Section of skin showing the eosinophilic halo cells among the tumor mass (H and E, ×600)

Figure 4

PAS staining of the tumor mass showing the PAS-positive cytoplasminc granules (×600)

Discussion

Granular cell tumor was first described by the Russian pathologist Abrikossoff in 1926 and hence also called Abrikossoff's tumor.[1] He thought that the tumor was of primitive striated muscle origin, and hence he called it as ‘granular cell myoblastoma.’ It presents in the second to sixth decade of life and is twice as common in women as in men.[2] It is relatively more common in colored people.[2] These tumors usually present as a slow-growing ulcerated nodular mass, located mainly in the subcutaneous tissue of the head and neck and the oral cavity, especially the tongue.[3] They have also been reported from the breast, respiratory tract, esophagus, and chest wall.[4] Multicentric tumors involving the tongue and parotid have been reported.[5] Granular cell tumors involving the skin and subcutaneous tissue comprise about 30% of all such tumors. A granular cell tumor in a child presenting as a nodular mass over a BCG vaccination scar has been reported.[6]

The histogenesis of the tumor is disputed. Various histochemical and ultrastructural studies propose the origin of the tumor to be from Schwann cells or less frequently from histiocytes, fibroblasts, or pericytes.[7] The general consensus now is that the cells are of neural or nerve sheath origin.[8]

Histopathology of the tumor shows polygonal cells arranged in sheets with granular eosinophilic cytoplasm and small nuclei.[9] Granularity of tumor cells is due to the accumulation of secondary lysosomes in the cytoplasm. This change is rather non-specific and can be observed in many non-neural tumors, including those arising from smooth muscle, connective tissue, neuroglia, endothelial, and epithelial cells. The cells are found to infiltrate the dermal connective tissue and the subcutaneous fat. The overlying epithelium may show pseudoepitheliomatous hyperplasia, and this may be confused with a squamous cell carcinoma.[10] Immunohistochemical studies have shown the cells to express S-100 protein, CD-68, nerve growth factor receptor-5 (NGFR-5), microphthalmia-associated transcription factor (MITF), inhibin α, neuron-specific enolase, and protein gene product (PGP) 9.5.[11] The cells are negative for myoglobin, HMB-45, and glial fibrillary acidic protein (GFAP).[12] An aggressive malignant form of granular cell myoblastoma that metastatizes is rare. It comprises of 1-3% of all reported cases of granular cell tumors.[9] There are no well-defined criteria for the diagnosis of malignancy. Tumor size > 5 cm, rapid growth, vascular invasion, necrosis and cell spindling are important indicators of malignancy.[13] Occurrence of metastasis, a very infrequent finding, is the only accepted criterion of malignancy, which is associated with a poor prognosis. There are also reports of GCT colocalized with a squamous cell carcinoma.[14]

Treatment of Abrikossoff's tumor consists of local surgical excision; recurrence is uncommon.[9] We report this case due to its unusual presentation in the form of a depressed “panniculitis-like plaque,” mimicking several other panniculitides.

What is new?

Our case of Abrikossoff's tumor presented in the upper arm, which is not a common site.

The tumor presented as a depressed panniculitis-like plaque, which is rare.