PMC9826554_01
Histological and inmunohistochemistry images from the lesion excised in the right foot in 2015. (a) Low magnification hematoxylin-eosin image (x4): Fragmented tissue showing epithelial cell proliferation growing in trabeculae and nests of diverse sizes, embedded in a dense fibrous stroma. The fragmentation of the sample does not allow to assess whether it presents an infiltrative or expansive growth or not. (b) Higher magnification hematoxylin-eosin image (x20): The lesion is composed of elongated, medium-sized cells with eosinophilic, focally clear, poorly delimited, and monomorphic cytoplasms, with rounded-oval nuclei, without nucleolus or nuclear atypia. Atypical mitoses are not identified. Occasionally, glandular pseudoluminas appear. (c) EMA focally positive. (d) Low Ki67 proliferative index. The diagnosis was hidradenoma.
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F1
We present the case of a 27-year-old woman with personal history of marginal surgical excision of a tumor in the sole of her right foot in 2015, which received the histopathological diagnosis of hidradenoma (Fig. 1).
Normal plain radiographs of the right foot.
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F2
First, we obtained plain radiographies of the right foot without finding signs of bone involvement (Fig. 2).
Magnetic resonance imaging performed on the right foot with data suggestive of malignancy. In the central region of the sole of the foot, with a cutaneous and subcutaneous location, a solid soft-tissue lesion measuring 24 x 11 x 17 mm is showed, with a spiculated contour, meeting some of the spicules with the plantar fascia and in contact with the flexor digitorum brevis. It is hypointense in T1 and somewhat heterogeneous, with an intermediate signal prevailing in T2-weighted sequences. In the post-contrast sequences, it presents an important enhancement, mainly peripheral, with a small spiculated part that contacts the plantar fascia that presents complete thickness and signal, as well as the flexor brevis muscle. No involvement of the lateral or medial plantar nerve or other adjacent vascular structures is seen. These findings suggest hidradenocarcinoma, considering the personal history of the patient.
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F3
Afterwards, a magnetic resonance imaging was performed showing a new subcutaneous lesion in the right foot sole (Fig. 3).
Histological and inmunohistochemistry images from inguinal lymph node excised in 2020. (a) Low magnification hematoxylin-eosin image (x4): A lymph node infiltrated at the subcapsular level is identified by a grandular proliferation, in nests, with little stroma and a clear eosinophilic appearance. (b) Higher magnification hematoxylin-eosin image (x20): Infiltrating lesion in the ganglion is observed. There are glandular structures, with little stroma between them, which form lumens with eosinophilic secretions inside. Cells with broad eosinophilic to clear cytoplasm and an irregular rounded-oval nucleus. (c) EMA intense and diffuse positivity. (d) Low Ki67 proliferative index. (e) Negative for androgen receptor. The diagnosis was hidradenocarcinoma metastasis.
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F4
Positron emission tomography-computed tomography performed as an extension study. Increased metabolic activity on soft-tissue injury in the right foot close to the plantar fascia, probably related to current tumor pathology. Right inguinal lymphadenopathy up to 2.2 cm with tenuous FDG uptake suggestive of malignancy. Adenopathies in the external iliac chain of up to 11 mm, with a slight increase in FDG uptake.
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F5
Images of circumferential surgical resection of the tumor with wide margins (>3 cm) and coverage of the defect with split-thickness skin autograft.
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F6
Since the defect was not located in a weight bearing surface, free flap or local flap reconstruction was not chosen (Fig. 6).
Split-thickness skin autograft covering foot sole completely healed after radiotherapy.
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F7
The defect was properly covered, and the patient started a normal life and daily standing work two months after completing radiotherapy treatment (Fig. 7).