Cytomorphological Diagnosis of Isolated Cutaneous Aspergillosis in an Immunocompetent Host.

Sir,

Aspergillosis is the second most common opportunistic fungal infection in humans, first being the candidiasis.[12] Usually, this infection is seen in lungs, central nervous system (CNS), paranasal sinuses, etc.[2] However, primary cutaneous aspergillosis (PCA) is rare and may occur as a primary or secondary infection. Most of the cases of PCA are observed mostly in immunocompromised patients. However, few cases have also been noted in immunocompetent individuals.[34] Here, we report a case of isolated PCA in an immunocompetent individual which was diagnosed on fine-needle aspiration cytology (FNAC).

A 68-year-old female presented with a swelling over the base of the thumb for last 10 months. The swelling had progressively increased in size over last few months. On examination, the swelling measured 1.5 cm × 1.5 cm and was soft to cystic, mobile and nontender [Figure 1]. The overlying skin was unremarkable. Clinically, a diagnosis of lipoma or ganglion was suggested. She gave a history of trauma following hit by a cricket ball on apex of thumb, 12 years back. However, she still had a visible cut mark at the same site. She was a housewife; however, she was often involved in gardening. There was no history of weight loss, fever, cough, intake of any steroids, or other immunosuppressive drugs or any debilitating or chronic systemic illness. The general and systemic examination of the patient did not reveal any abnormality.

Figure 1

A nodular swelling at base of the right thumb

FNAC was done from the thumb swelling using a 22-gauge needle and yielded 2 mL of blood mixed pus. Multiple smears prepared were air dried and fixed in 95% ethyl alcohol and subsequently stained with Giemsa and Papanicolaou (Pap) stains respectively. The smears prepared showed acute and chronic inflammatory cells, cystic macrophages, and multinucleated giant cells in a necrotic background [Figure 2a]. Also, noted were many septate fungal hyphae with acute angle branching [Figure 2b and c], which showed positive staining on Periodic acid-Schiff (PAS) [Inset, Figure 2c]. The cytomorphological features were consistent with Aspergillus spp. The pus aspirated was sent for culture study and confirmed the growth of Aspergillus flavus on sabouraud dextrose agar (SDA) medium at 37®C & 25®C for 72 h. Also, the strain isolated was susceptible to the following antifungals tested: Itraconazole, amphotericin B, terbinafine, and echinocandins.

Figure 2

(a) Smear shows dense inflammation, cystic macrophages, and multinucleated giant cell in a background of necrosis (Pap, ×20). (b and c) Septate fungal hyphae branching at acute angle (b - Pap, ×40 and c - Giemsa, ×40); Inset, (c) shows periodic acid–Schiff (PAS) positive fungal hyphae

The patient was further investigated. Her hemogram revealed eosinophilia (absolute eosinophil count—824/μL). However, rest of the hematological parameters and other routine biochemical investigations were within normal limits. X-ray paranasal sinus, chest X-ray, and abdominal ultrasound were normal in study. The patient was found to be HIV negative with CD4 counts of 950 cells/mm3. The patient was treated with oral antifungal drugs (Tab itraconazole, 200 mg; two times a day) and showed marked improvement with regression of the swelling in 7–10 days.

Aspergillusspecies is a known ubiquitous fungus and can exist in soil, water, and decaying vegetations. Only a few are pathogenic to human beings. The systemic infections are commonly caused by A. fumigatus and A. flavus and cutaneous aspergillosis is usually caused by A. flavus, A. fumigatus, and rarely by A. niger, A. terreus, A. ustus and A. chevalieri.[34] The primary forms usually occur due to direct inoculation at the site of injury after surgical procedure, trauma, burns, etc.[13] There are few predisposing factors which can aid in the causation of PCA like steroids and immunosuppressive drugs, prematurity in neonates along with working in moist warm environment for prolonged periods.[23] In our case, the patient gave history of trauma to thumb 10 years back which may not be significant but the cut mark adjacent to the present swelling may have acted as a portal of entry. Secondary cutaneous lesions can be noted because of contiguous extension to skin from infected underlying structures or from hematogeneous spread.

The cutaneous lesions have variable nonspecific presentations. It may present as a violaceous macule, papules, plaques, subcutaneous nodules, hemorrhagic bullae, ulcerations with necrosis and pustules or abscess.[34] Usually, these are noted in immunocompromised individuals with hematogenous dissemination. Burik et al.[5] reported a spectrum of cutaneous aspergillosis in immunocompromised patients having HIV-AIDS, burn victims, neonates, individuals with cancer, bone-marrow, and solid organ transplant recipients. Rare case reports also mentioned about the extensive cutaneous involvement in PCA.[36]

The diagnosis of cutaneous aspergillosisrequire demonstration of the fungus with special stains like Gomori methenamine silver and PAS. Sometimes fruiting structures like head and conidia of Aspergillus species can also be seen. However, culture is considered the gold standard. We should consider different infectious and noninfectious causes of swelling in the thumb regions while evaluating the patient. Various infectious causes can be fungal, bacterial, or parasitic. The noninfectious ethologies which should be kept in mind are lipoma, fibroma, ganglion, arthritis, neuroma, giant cell tumor, hemangioma, etc. In all these cases, proper clinicoradiologic correlation is essential in conjunction with cytohistological examination.

The diagnosis of Phaeohyphomycosis should also be kept as one of the differentials while evaluating these lesions. The presence of filamentous fungi on Potassium hydroxide (KOH) examination and yeast like cell on Masson-Fontana stain (highlights the presence of melanin in fungal hyphae) confirms the diagnosis of Phaeohyphomycosis.

The treatment of aspergillosis is primarily with antifungal agents like amphotericin B and itraconazole.[67] However, the treatment of PCA is not well defined. It may comprise of both medical and surgical modality depending on the size and site of the lesion. In our case, the patient responded well to the medical treatment. The immunocompetent host developing a solitary lesion of PCA after trauma have a favorable outcome.[567]

Considering the rarity and isolated presentation of PCA, it can be considered as a separate disease entity if no other significant primary disease is present in the patient. However, more studies are needed to validate this finding.

The reports of PCA in immunocompetent host is rare and FNAC with ancillary investigations can prove useful for early diagnosis in a clinically unsuspected case of cutaneous aspergillosis.

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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initial will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

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Conflicts of interest

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