CD30+ extranodal natural killer/T-cell lymphoma mimicking phlegmonous myositis: A case report

The current study presents a case of a 23-year-old male with CD30+ nasal-type extranodal natural killer/T-cell lymphoma (NKTL), with unusual clinical features mimicking phlegmonous myositis. The patient initially presented with swelling and tenderness of the left lower limb, particularly around the left ankle. One month later, pharyngalgia and fever developed and the patient was treated with antibiotics for the phlegmonous inflammation, however, the symptoms were not relieved. A muscle biopsy was performed on the lesion and revealed diffuse infiltration of atypical lymphoid cells with irregular nuclei. Immunohistochemistry showed staining for CD3ɛ(−), CD20(−), CD45(+), CD30(+) and CD56(+) presented with positive staining for certain tumor cells, granzyme B(+), activin receptor-like kinase 1(−), Ki-67(+) and Epstein-Barr virus-encoded small RNA(+), which indicated nasal-type extranodal NKTL. The present case emphasized that extranodal NKTL may be a rare cause of phlegmonous inflammation and fever of undetermined origin.


Introduction
Nasal-type extranodal natural killer/T-cell lymphoma (NKTL) is a rare type of lymphoma, which is associated with the Epstein-Barr virus (EBV). NKTL has also been referred to as lethal midline granuloma and polymorphic reticulosis. When NKTL occurs outside the nasal cavity, such as in the skin, soft tissue, gastrointestinal tract and other extranasal sites, it may have various presentations (1)(2)(3)(4)(5)(6)(7). As a result of advances in immunohistochemistry, the disease can now be more easily identified. The current study presents a case of a 23-year-old male with CD30 + nasal-type extranodal NKTL, with skeletal muscle involvement mimicking phlegmonous myositis and fever of undetermined origin (FUO). In addition, the diagnosis of extranodal NKTL and FUO is discussed. The patient provided written informed consent.

Case report
Patient history. In August 2011, a 23-year-old male presented with swelling, tenderness and high skin temperature of the left lower limb, particularly around the ankle as the patient did not have a fever the patient did not seek treatment. However, one month later, pharyngalgia and fever developed and the patient was treated with antibiotics for the inflammation at a local health center, however, the symptoms were not improved. The patient was subsequently transferred to the Chengdu First People's Hospital (Chengdu, China) for hospitalization.
Treatment and further testing. Multiple antibiotics were administered continuously, however, the patient showed no clinical response. During hospitalization, the patient's condition deteriorated, with the highest temperature reaching 40.4˚C and weight loss of 5 kg over two months. The patient was referred to the Infection Disease Center (West China Hospital, Chengdu, China) due to FUO. On physical examination, purulent secretion was found in the patient's nose and the spleen was palpable 5 cm below the costal margin. The laboratory tests (22 Aug, 2011) showed a WBC count of 1.57x10 9 /l (36.5% neutrophils), platelet count of 71x10 9 /l, ALT levels of 184 IU/l, AST levels of 197 IU/l, LDH levels of 554 IU/l and γ-glutamyltransferase levels of 432 IU/l.
Computed tomography, magnetic resonance imaging and biopsy. A computed tomography scan of the laryngopharynx

CD30 + extranodal natural killer/T-cell lymphoma mimicking phlegmonous myositis: A case report
identified inflammatory changes, particularly in the left nasopharynx and the soft palate, as well as hyperplasia of the submandibular lymph nodes. Magnetic resonance imaging of the lower extremity detected a diffuse infiltrative lesion, mimicking phlegmonous myositis (Fig. 1). A bone marrow biopsy was performed again and showed a depression with normal morphology. Prominent ulceration and necrosis with fungal elements (usually oidiomycetic) were observed in the soft palate by pharyngoscopy. Taking into consideration the fever, ulceration in the nasopharynx, splenomegaly, weight loss and cachexy, the diagnosis of extranodal NKTL was determined. In addition, the muscle biopsy of the left limb and repeat biopsy of the pharynx was of concern. Diffuse infiltration of medium-sized atypical lymphoid cells with irregular nuclei was shown in the gastrocnemius biopsy.
Follow-up. Based on the clinical manifestations and pathological observations, a diagnosis of nasal-type extranodal NKTL was determined and the patient was transferred to the Department of Hematology (West China Hospital, Chengdu, China) for chemotherapy with GL-IDE: Gemcitabine (1.6 g on days 1 and 8); L-asparaginase (10,000 U/m 2 on days 4, 6, 8 and 10); Ifosfamide (1.6 g on days 1, 2 and 3); Dexamethasone (20 mg on days 1, 2, 3 and 4); Etoposide (160 mg on days 1, 2 and 3) . The patient succumbed as a result of the rapid progression of the disease two months later.

Discussion
Nasal-type extranodal NKTL has also been referred to as lethal midline granuloma or polymorphic reticulosis and may have variable presentations depending on the predominant site of involvement. To date, only sporadic cases concerning skin, muscle and ocular involvement have previously been reported (1-4). Min et al (5) reported a case of extranodal NKTL with muscle involvement that initially manifested with granulomatous myositis, with a normal CBC count and without fever. In addition, Paik et al (6) reported a case of extranodal NKTL with skeletal muscle involvement and heavy eosinophilic infiltration, with a peripheral blood eosinophilia   of 22.2% on CBC count. However, the current patient presented with swelling, tenderness and a high skin temperature of the left lower limb, followed by hyperpyrexia. The patient's WBC count reached 10.79x10 9 /l (84.6% neutrophils and 0% eosinophils), which mimicked phlegmonous myositis. The present case illustrated the requirement for caution when diagnosing NKTL as it may be a rare cause of unexplained phlegmonous myositis, particularly when accompanied with FUO and symptoms in the nasopharynx.
Extranodal NKTL is characterized by vascular damage, prominent necrosis and is associated with the EBV (7,(9)(10)(11). The typical immunophenotype for extranodal NKTL is CD2 + , CD56 + , surface CD3and cytoplasmic CD3ε + , as well as positivity for cytotoxic molecules (granzyme B, T-cell intracellular antigen 1 and perforin) (13)(14)(15). As observed in the present case, early biopsy may give a false indication of an inflammatory disorder due to the paucity of neoplastic cells; however, in NKTL, a large number of inflammatory cells are recruited by the innate natural killer cell immune response and extensive necrosis is caused by angiodestructive tumor cells. However, in the present study, the repeat biopsy (which showed atypical lymphoid cells positive for granzyme B, EBER, CD45 and CD56, and negative for CD20 and ALK1) showed features that were consistent with NKTL. This emphasized the requirement for a repeat biopsy when NKTL is suspected, as necrosis is often present in biopsy. The biological meaning for the positivity of CD30 is not clearly understood. As CD30 is normally associated with anaplastic large cell lymphoma, the positivity for CD30 has been reported in few cases of cutaneous NKTL. The present case showed that extranodal NKTL must be considered as a differential diagnosis of CD30 + and CD56 + lymphoma.
In conclusion, in patients who exhibit FUO, infectious diseases, malignancies, collagen vascular diseases and a variety of miscellaneous disorders must be considered. The cause of FUO is partially age-related and neoplastic disorders have replaced infectious diseases as the most common cause of FUO; non-Hodgkin's lymphoma is the first cause of FUO that has been linked to cancer (16,17). Although neoplastic disorders are more commonly observed in elderly patients, the present patient was 23-years-old, which is relatively different from the median age (50 years) of those with NKTL, indicating that NKTL is occasionally found in younger patients.