Fine needle aspiration cytology of unilesional mycosis fungoides d'emblee.

Primary cutaneous T-cell lymphoma is a rare lymphoproliferative disorder accounting for 2% of all lymphomas. Mycosis fungoides (MF) is a rare, albeit commonest form of primary cutaneous T cell lymphoma. MF d'emblee is an uncommon variant which is easily mistaken clinically for epithelial malignancy. Diagnosis at cytology is challenging due to low degree of suspicion, rare occurrence and diverse morphology. We report a case of 51-year-old male presenting with a solitary nodulo-ulcerative lesion over right thigh. Smear showed atypical lymphocytes with hyper-convoluted cerebriform nuclei along with few mature lymphocytes consistent with MF. To our knowledge, this is the first report of unilesional MF d'emblee diagnosed at fine needle aspiration cytology (FNAC). Our case emphasizes that FNAC is an accurate method for early diagnosis and clinical staging of patients with MF.

Introduction

Primary cutaneous T cell lymphoma (PCTCL) is a spectrum of diseases composed of malignant clonal helper T lymphocytes. Mycosis fungoides (MF) is a rare, albeit commonest form of PCTCL. MF d’ emblee is an uncommon variant of MF, which is characterised by rapid development of tumors without a patch or plaque stage disease.[1] MF needs to be distinguished from other PCTCL as the latter needs aggressive line of management. Studies describing the role of fine needle aspiration cytology (FNAC) in the evaluation of lymphadenopathy associated with PCTCL are on record.[2] However, very few case reports describe the cytomorphology of MF.[3] The present case emphasizes the role of FNAC in the early diagnosis and staging of patients with MF.

Case Report

A 51-year-old male patient presented to surgery OPD with history of wound over lateral aspect of right thigh of 3 months duration. The lesion was initially nodular; later the lesion underwent ulceration. There was no history of fever, weight loss, any drug intake or similar lesions at other sites in past. On examination, a solitary nodulo-ulcerative lesion was seen over the lateral aspect of right thigh, measuring 7 × 5 cm. Ulcer was covered with necrotic slough.

On systemic examination, a small inguinal lymph node measuring 1 × 1 cm was noted. There was no evidence of lymphadenopathy at other sites or hepatosplenomegaly. Clinically, a provisional diagnosis of squamous cell carcinoma or malignant melanoma was made.

Peripheral smear was normal. Ultrasound abdomen and whole body computed tomography scan was unremarkable. The patient was HIV negative.

FNAC of the lesion was done. Smears showed atypical lymphoid cells in dispersed pattern admixed with few mature lymphocytes [Figure 1a]. Atypical cells had scanty cytoplasm, nucleus with irregular hyperconvoluted nuclear membrane, coarse chromatin, and at places prominent nucleoli [Figure 1b]. FNAC of inguinal lymph node showed reactive hyperplasia. Hence, at FNAC, the possibility of MF was suggested. Incisional biopsy and later excision were done.

Figure 1

(a) Cytology smear showing dispersed population of lymphoid cells admixed with fibrous stroma (Pap, ×40). (b) Cytology smear showing atypical lymphoid cell with cerebriform nucleus and prominent nucleoli (Pap, ×1000). Inset shows CD4 positivity in tumor cells (IHC, ×400)

Specimen consisted of skin-covered soft tissue mass measuring 8.5 × 8 × 3 cm. External surface showed a large ulcer filled with necrotic material, measuring 5 × 5 cm. Cut surface was grey white.

Histopathological examination revealed skin with focal ulceration covered with necrotic slough and plenty of fungal hyphae embedded in it. Epidermis showed hyperkeratosis and epidermotrophism in the form of atypical lymphocytes with irregular hyperconvoluted, cerebriform nuclei in the epidermis and similar cells in a band-like pattern tagging at the dermoepidermal junction. Papillary dermis showed coarse fibrosis and atypical lymphocytes in sheets extending into the mid dermis. Marked pigment incontinence was noted as were atypical mitosis. Immunohistochemistry showed positivity for leukocyte common antigen (LCA), CD3 and CD4 [inset in Figure 1b] and CD20, CD8 and CD30 were negative.

Hence, a final diagnosis of unilesional MF d′ emblee (stage IIb) with fungal infection was made.

Discussion

MF is a rare, albeit commonest form of PCTCL, with the incidence being 0.36–0.4 cases per 105 of the population in USA.[4] Alibert first coined the term in 1806 for its mushroom like growth that may develop in the terminal stages of disease. The outcome of disease is highly unpredictable and management depends on the stage of the disease.

It occurs most commonly in fifth to sixth decade of life, however, no age is an exception. Clinically, classic MF lesions are multiple and evolve into three stages – patch, plaque and tumor stage. However, this is an arbitrary classification as there is considerable overlap both clinically and histopathologically. Rare case reports describing solitary lesions of MF occurring on trunk have been published.[56]

MF d’ emblee is an extremely rare variant of MF which is characterized by development of tumor without a background of patch or plaque stage. These tumors eventually undergo ulceration and superimposed infection, as in our case.

The most common sites affected are, trunk, breast, extremities, flexures and rarely palms and soles.[7] 70% of patients have palpable lymph node at presentation, most commonly axillary and inguinal group. Patients with lymph node involvement and visceral disease have poor prognosis.

Many studies describe the role of FNAC in the diagnosis of lymphadenopathy associated cutaneous T cell neoplasm.[2] However, very few case reports describe the role of FNAC in primary diagnosis of MF. Ludwig and Balachandran[8] described the cytological findings in a case of MF with pulmonary involvement. Bronchial smears showed malignant lymphocytes with hyperchromatic nuclei showing indentation and grooving.

According to Lutzner et al.,[9] MF cells vary greatly in size. At times, they are small and indistinguishable from small lymphocytes. Thus, these cells can be easily missed at light microscopy. However, they have hyperconvoluted nuclear membrane giving it a cerebriform appearance. Some MF cells are large and some are intermediate in between. In our case, smears showed large atypical lymphocytes with deep and tortuous nuclear membrane, giving the characteristic cerebriform appearance, peripherally distributed chromatin and single prominent nucleolus. Careful attention to these features at cytology will help to diagnose MF accurately.

At immunohistochemistry, the neoplastic T cells typically express CD3 and CD4 positivity, while CD7 and CD8 are negative.

Controversy exists as to the exact nature of the unilesional MF. Some consider it as a reactive process while some attribute it to the drug intake. However, typical systemic MF does not develop in them, though local recurrence is seen in 10% cases.[10] Frontiers remain with still questionable nature about the lesion.

In summary, unilesional MF d’emblee should be considered in the differential diagnosis of a non-healing nodulo-ulcerative lesion of thigh. Though scepticism exists, FNAC is a useful modality in the early diagnosis and clinical staging of MF. A close coordination between clinician and pathologist is imperative for early diagnosis and prompt treatment.