Subcutaneous panniculitis-like T-cell lymphoma: an unusual cause of right thigh hypertrophy

Abstract

A man in his mid-20s presented with a painless swelling over his right thigh, which had been progressively increasing over 3 years. He underwent an excisional biopsy for the same, which showed reactive lymphadenopathy. Since the last year and a half, he developed a lower abdominal wall swelling with mild redness over it. In addition, over the last few months before presentation to haematology outpatient clinic, he experienced bouts of fever, night sweats, anorexia, weight loss and right inguinal lymphadenopathy. On examination, splenomegaly was identified. In view of the patients’ symptoms, he underwent a positron emission tomography scan, which showed hypermetabolic activity in the subcutaneous tissue sparing the lymph nodes and spleen. A deep skin punch biopsy taken from his right thigh was consistent with the diagnosis of subcutaneous panniculitis-like T-cell lymphoma αβ T-cell phenotype. The patient was treated successfully with oral steroids and on routine follow-up, he is in remission for 5 years.

Background

Panniculitides is a heterogeneous group of inflammatory diseases involving the subcutaneous fat. Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is a rare type of cytotoxic T cell lymphoma, with (α/β) T cell receptor (TCR) phenotype.^{1 2}

SPTCL has a distinct feature of involvement of only subcutaneous fat mimicking panniculitis, without involvement of the lymph nodes and spleen. The main clinical manifestation of SPTCL is the presence of subcutaneous nodules in the extremities and the trunk.^{3 4}

The pathological features of SPTCL include lobular pattern of lymphocyte infiltration around adipocytes with sparing of interlobular septa, epidermis and dermis. Immunophenotyping shows CD8 positive and CD4, and CD56 negative cells.⁵ The diagnosis is usually delayed as SPTCL mimics other common conditions like eczema, benign panniculitis and cellulitis. SPTCL usually has an indolent course with excellent prognosis, however, rarely when associated with haemophagocytosis it is more aggressiv.⁵ SPTCL differs from cutaneous γ/δ T-cell lymphomas.^{1 2}

Here, we present a case of SPTCL presenting as long-standing hypertrophy of the thigh with no apparent skin change, sparing the spleen and lymph nodes.

Case presentation

A man in his mid-20s presented to the haematology outpatient clinic (HOC) with a 3-year history of progressive painless swelling of his right thigh, associated with night sweats and right inguinal lymphadenopathy. In addition, he had bouts of fever, anorexia and weight loss. Before presentation to HOC, the patient was initially seen by a dermatologist who prescribed oral antibiotics but without improvement. After that, the patient was evaluated by a general surgeon who performed a right inguinal excisional lymph node biopsy which showed a reactive pattern in the lymph nodes and a Doppler ultrasound of the right thigh, which did not show any evidence of thrombosis. A year and a half later, he developed a swelling over his lower abdominal wall with mild redness over it.

On examination, the patient had a non-tender swelling and subcutaneous induration over his right thigh and lower abdomen, with no visible redness on his thigh and mild abdominal redness (figure 1A–C). The spleen was palpable (spleen tip 5 cm below costal margin) and right inguinal lymphadenopathy was present.

Figure 1.

(A–C) Gross physical appearance: showing right thigh hypotrophy (A, B), showing lower abdominal swelling with mild redness (C).

The main reason why the patient sought medical advice was his concern regarding his right thigh hypertrophy and nigh sweat.

Investigations

Given the patient’s above history, a complete blood panel evaluation was carried out. He had a haemoglobin of 123 g/L with a total white cell count of 2.3×10⁹ /L and a normal platelet count. Serum lactate dehydrogenase (LDH) was raised 1080 U/L. He had a C reactive protein of 26 mg/L and ANA titre of 1:80. His liver and kidney functions were normal with negative blood cultures. An echocardiogram was negative for vegetation. Antineutrophil cytoplasmic antibodies myeloperoxidase (ANCA MPO) and ANCA PR3 were negative, rheumatoid factor and anticyclic citrullinated peptide were negative. Antiphospholipid and anticardiolipin were negative.

The patient then underwent radiological investigations in an attempt to achieve a diagnosis. A whole-body CT scan showed soft tissue thickening and stranding in the subcutaneous tissues of the lower abdominal wall and right lateral aspect of the gluteal region (figure 2A, B). Splenomegaly with soft tissue thickening and stranding was noted in both inguinal regions with lymphadenopathy. MRI show oedema, thickening and enhancement in the same region (figure 2C).

Figure 2.

(A–F) Radiological findings showing CT scan of abdomen and pelvis shows subcutaneous tissue thickening (white arrows) and splenomegaly (A, B). MRI showing oedema, thickening and enhancement (white arrows) (C). PET scan shows hypermetabolic activity in right subcutaneous thigh region and lower abdomen sparing the spleen (D–F). PET, positron emission tomography.

Positron emission tomography (PET) scan showed hypermetabolic activity in the lateral aspect of the right gluteal, lower abdominal wall and right inguinal lymph nodes. The was no metabolic activity in the spleen (figure 3D–F).

Figure 3.

(A) Deep skin punch biopsy showing lymphocytic infiltrated by lymphocytes in lobular distribution in some areas surrounding the adipocytes with bulging inside the cytoplasm of the adipocytes (rosette like). The lymphocytic infiltrate is immunoreactive for CD3 and CD8 markers and negative for CD20, CD56, CD34 and CD117. Scattered histiocytes were identified using CD68 immunohistochemical marker (figure 3I).

A deep skin punch biopsy of the right thigh wall with H&E stain showed subcutaneous tissue that was infiltrated by lymphocytes in lobular distribution causing rosette-like bulging of the cytoplasm of some adipocytes (figure 3A). The lymphocytic infiltrate was immunoreactive for CD3 and CD8 markers and negative for CD4, CD20, CD56 and CD 117 markers, which is consistent with α/β SPTCL (figure 3B–H). Scattered histiocytes were identified using CD68 immunohistochemical marker (figure 3I).

Right inguinal lymph node biopsy showed a reactive pattern. Bone marrow biopsy showed no lymphoma involvement, and no evidence of haemophagocytosis. Owing to our limited resources the TCR gene rearrangement analyses was not possible.

Differential diagnosis

Thigh swellings can have varying diagnosis which include lipoma, benign panniculitis, subcutaneous anaplastic large cell lymphoma, peripheral T cell lymphoma, lupus erythematosus panniculitis, deep venous thrombosis and cellulitis. A thorough clinical evaluation along with radiological and pathological analysis helped us to rule out all the above diagnoses and finally arrive at the diagnosis of SPTCL.

Treatment

The patient was offered a choice of treatment with chemotherapy, local radiotherapy and/or steroids. He opted for the steroids-only treatment and was started on prednisolone 30 mg for 4 weeks with dose tapering.

There are different treatment modalities available for SPTCL with no consensus on the ideal mode of treatment. Chemotherapy, local radiotherapy as well as steroids are the options available. After discussion with the patient, he was started on an oral dose of prednisolone 30 mg a day for 4 weeks and the dose was gradually tapered off over a course of 2 weeks.

Outcome and follow-up

Once steroids were tapered off the patients’ blood parameters returned to normal. There was a significant decrease in the size of the right thigh swelling and well as reversal of splenomegaly.

The patient was followed up over 5 years and showed excellent response to steroid therapy.

Discussion

The WHO-European Organisation for Research and Treatment of Cancer restricted the term SPTCL to α/β SPTCL.¹

This form of SPTCL is relatively rare and constitutes less than 1% of all cutaneous lymphomas, besides this, an overlap of clinical findings with other common medical conditions such as benign panniculitis, dermatitis, lipoma, cellulitis and deep venous thrombosis lead to a delay in diagnosis in our patient.⁵

PET scan shows a distinctive pattern in SPTCL with hypermetabolic activity in the subcutaneous tissue sparing the spleen and lymph nodes despite presence of splenomegaly and lymphadenopathy as shown in our patient. We confirmed our diagnosis of SPTCL with a deep punch biopsy of the skin, which showed T lymphocytes infiltrating the adipose tissue. These T cells were CD8 positive and the coexpression CD4 and CD56 were negative, which is diagnostic of SPTCL.

Clinically, our patient had minimal redness over the abdominal skin with no other skin changes. Despite the long history of induration over the thigh, no skin ulceration was found. This is particularly important to differentiate SPTCL from other type of lymphoma involving the skin in particular cutaneous γ/δ T-cell lymphomas, which may involve the subcutaneous tissue, epidermis and dermis, and may develop superficial ulceration.^{6 7} The appearance of the subcutaneous pattern of cutaneous γ/δ T-cell lymphomas may look like SPTCL but the immune histochemistry is CD56 positive, and CD4 and CD8 negative. The course of cutaneous γ/δ T-cell lymphomas is more aggressive with very poor prognosis.⁸

SPTCL can affect more than one site so it can be unifocal and multifocal as in our patient.

Bone marrow examination is important for staging the diseases and to find any evidence of haemophagocytosis which may be a complication SPTCL and carries a poor prognosis.^{9 10} No standard treatment protocols for SPTCL currently exist; hence, treatment needs to be individualised. Systemic steroids are possibly the best choice for first-line therapy of localised SPTCL.¹¹ Our patient with SPTCL had an indolent course with excellent response to steroids and no evidence of relapse after 5 years of treatment.

In general, SPTCL is a rare condition, which needs to be diagnosed accurately as it has an excellent prognosis, especially when not associated with haemophagocytosis.

Learning points.

• A deep skin punch biopsy plays the most important role in the diagnostic work up of subcutaneous panniculitis-like T-cell lymphoma (SPTCL).

• SPTCL is not associated with lymph node or spleen involvement.

• Oral steroids can be used as the initial treatment for SPTCL.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).