Wiki "Not a lipoma" excision?

[wtcg2k]

I'm a little stumped on how to code this. The patient was undergoing the excision of an ankle lipoma, but the diagnosis changed. The procedure still seems consistent with 27618 or 27632 (preop Dx gives measurement as 4cm, but no measurements are given in op note), but the surgeon very explicitly states that it is a cyst and not a lipoma. Pathology states that some of the excised tissue is compatible with a lipoma, but other tissue could be a cyst.

I'm still kind of inclined to code one of the soft tissue excisions with a lipoma diagnosis based on the pathology report, though that's largely because I'm not sure what else would apply. M25.872 for an unspecified cyst?

Op note:

PREOP Dx: lipoma left lateral ankle 4cm

POSTOP Dx: left lateral ankle cyst

SURGERY: excision of left ankle cyst

SPECIMEN: cyst capsule/fatty tissue

[...] The patient was then brought to the OR and placed in the supine position. Once satisfactory anesthesia was given, the left lateral ankle was then prepped and draped in a sterile fashion. Attention was then paid to the lipoma. The skin was then localized and incision was made and dissection was carried down to the lipoma using electrocautery. There was a thick capsule - this was punctured and a thick white gelatinous fluid was expressed - it was not a lipoma. The capsule was grasped and circumferentially dissected free with electrocautery - it was completed excised from the subcutaneous tissue. The surrounding fatty tissue was also excised. The specimen was then removed and sent to pathology. The cavity was then irrigated and hemostasis was achieved with electrocautery. The incision was then closed with 3-0 Vicryl suture in the deep dermis and the skin was closed with 4-0 Monocryl suture. Skinaffix was then placed. [...]

Pathology:

Left ankle cyst, excision:

Lobulated adipose tissue, compatible with small lipoma.

Adjacent fibroconnective tissue with focal synovial type lining, potentially representing small ganglion/synovial cyst.

Negative for malignancy.