Peripheral T Cell Lymphoma of Parotid Gland: A Diagnostic Challenge

Abstract

Peripheral T-cell lymphoma of salivary gland is a rare clinical entity most commonly involving the parotid gland and mimics a salivary gland carcinoma. It has an aggressive clinical course with poor prognosis. Majority of the cases are diagnosed after surgical excision whereas the principal treatment is non-surgical (chemotherapy). Core biopsy is an excellent method of identifying these indeterminate lesions pre-operatively which would avoid unnecessary surgical intervention. We present a case report with diagnostic challenge in identifying peripheral T cell lymphoma of salivary gland with the review of literature.

Introduction

Peripheral T-cell lymphoma of salivary gland is a rare entity comprising 5–10% of Non-Hodgkin lymphomas and accounts for 1–3% of malignant salivary gland neoplasms [1]. It is usually seen in the parotid gland and can mimic a salivary gland carcinoma. Chemotherapy is the treatment of choice [2], however most of the cases undergo surgical resection first and the true diagnosis is achieved later. They are aggressive tumors with median survival rate of 1 year [2, 3]. We present a case report with diagnostic challenge in identifying peripheral T cell lymphoma (PTCL) of salivary gland with the review of literature.

Case Report

A 65 year old female presented with complaints of swelling in front of the left ear for 6 months with history of sudden increase in size, pain and redness over the swelling for past 2 months. On examination, 5 × 4 cm hard swelling with skin changes and fixity to skin over the left parotid region was seen (Fig. 1). Facial nerve was normal and there was no palpable cervical lymphadenopathy. Ultrasound parotid showed an enlarged left parotid gland with necrotic and calcific foci without increased vascularity or cervical lymphadenopathy. MRI revealed a 50 × 40 × 48 mm size solid mass with mixed signal intensity in the superficial and deep lobe of left parotid gland with few cystic areas (T1 and Fat suppressed T2 weighed images). Surrounding skin involvement and deep muscle involvement of temporalis and masseter with involvement of facial nerve was noted (Fig. 2). FNAC of the mass showed moderately cellular tumor cells with high nuclear cytoplasmic ratio, hyperchromatic nucleus with prominent nucleoli, suggestive of poorly differentiated carcinoma or high grade Mucoepidermoid carcinoma.

Fig. 1.

Tumor with skin involvement

Fig. 2.

MRI showing tumor with skin and underlying muscle involvement

The patient was counselled and underwent left extended total parotidectomy with left level II lymph node sampling with reconstruction of skin with cervico-facial flap. Intra operatively a 10 × 6 × 5 cm tumor was found involving superficial and deep lobes of left parotid with encasement of upper division of facial nerve and underlying temporalis and masseter muscle involvement (Fig. 3). Final HPE showed lymphoid neoplasm infiltrating and destroying the salivary tissue with extension to the overlying skin with atypical lymphoid cells arranged in diffuse pattern infiltrating the skeletal muscle, subcutaneous fat and dermis with perineural invasion. These findings were consistent with Lymphoproliferative disorder favoring High grade Non-Hodgkin Lymphoma (Fig. 4). Immunohistochemistry study revealed that tumor cells were immuno-positive for LCA, CD3, CD5, CD30 with focal and weak expression of BCL2 and Ki-67 labelling index of 80–90% which lead to the diagnosis of Peripheral T cell Lymphoma, NOS type (Fig. 5). WBPET-CT scan was done which showed a localized disease to the left parotid (Stage I–E). The case was discussed in the institutional Multidisciplinary committee and was planned for chemotherapy with CHOP-E regimen of 6 cycles with each cycle 3 weeks apart. She is presently on regular follow-up for past 6 months without evidence of disease.

Fig. 3.

Intra-operative image showing tumor encasing the upper division of facial nerve

Fig. 4.

Microscopic image (haematoxyllin and eosin stain- × 40 magnification) showing atypical lymphoid cells in diffuse sheets

Fig. 5.

IHC staining (IHC stain- × 40 magnification) showing atypical lymphoid cells are positive for LCA, CD3 and CD5

Discussion

Non-Hodgkin lymphoma is a lymphoproliferative disorder involving either T or B cells. Peripheral T cell lymphoma NOS is one of the subtypes of Non-Hodgkin lymphoma (NHL) of T-cell origin [1]. It is a rare clinical entity and parotid is the most common salivary gland involved (50–60%) followed by submandibular gland. Peripheral T-cell lymphoma (PTCL) may either originate in salivary gland tissue or from intra-glandular lymph nodes of the parotid gland. PTCL arising from the salivary gland tissue is very rare and to our knowledge, there are only 18 cases reported in English literature [4].

PTCL is more common in males, oriental population [2, 3, 5] with median age of presentation at 59 years [3]. An association with EBV is seen in 50–75% of cases. Other associated conditions are autoimmune conditions like Sjogren’s (40–70%), chronic sialadenitis (10–16%), enteropathy (5–8%) and pre-existing Warthin’s tumor (2–10%) [2, 3]. The clinical presentation includes swelling in the region of parotid, dryness of mouth, recurrent sialadenitis and B symptoms (fever, night sweats and weight loss) [3].

Routinely the patient with parotid tumor undergo radiological and histological evaluation. USG/CECT/MRI are the usual modalities and the choice of investigation depend upon the nature and extent of the disease [6]. Ultrasound is the primary imaging investigation of choice with MRI reserved for large, complex or possibly malignant tumors. MRI has superior tissue delineation as well as advantage of identifying perineural invasion. In the review of cases in the literature, there are no specific features suggestive of PTCL as was also seen in our case.

FNAC is the accepted and widely used initial investigation but its diagnostic accuracy is low. Except in specialty centers, significant variation in results with high level of inadequate diagnosis as well as missed malignancies is common. Sensitivity for detecting malignancy is 70–80% and the non-diagnostic rates are from 14 to 56% [7].

Ultrasound guided core biopsy is a safe and successful technique for diagnosis of parotid lesion where FNAC is non-diagnostic. Sections from core biopsy can be used for grading, staging and IHC allowing planning of appropriate surgical or non-surgical management [8]. Complications of this invasive technique include tumor seeding, bleeding and pain as compared to FNAC. Ultrasound guided core biopsy has sensitivity of 92–94% and specificity of 99–100% in diagnosing parotid tumors and help in treatment plan, type and extent of excision [7–9]. This procedure would be useful in identifying the condition like lymphoma pre-operatively and would have changed the treatment plan in our patient.

NHL is staged as per Ann-Arbor’s staging system. Treatment for PTCL of parotid is Chemotherapy [5] with CHOP+/−E Regimen (Cyclophosphamide, Danorubicin, Vincristine, Prednisolone, Etoposide). PTCL of parotid has an aggressive clinical course and worst prognosis than the B-cell lymphomas [3]. They have increased relapse rate with survival rate of 25–85% (6–48 months) [2]. EBV, Sjogren’s disease, CD-56 positivity are associated with poor prognosis (25–40%) [10].

Conclusion

PTCL is a rare clinical entity which poses a diagnostic challenge. Majority of the cases are diagnosed after surgical excision whereas the treatment is non-surgical (chemotherapy). Core biopsy is an excellent method of identifying these indeterminate lesions pre-operatively which would avoid unnecessary surgical intervention. The core biopsy has the advantage of providing adequate tissue for IHC evaluation, tumor typing and sub-typing with minimal side effects. We recommend that core biopsy should be preferred in cases with suspicious FNAC reports as it improves the diagnostic accuracy and obviate the need for morbid surgical procedures.